Cold start idle problem - running lean?

[aec]

I can't seem to get my van (1.9DG with Pierburg 2e3) to idle when cold.  It will fire up first turn of the key but won't idle without throttle until warmed up a bit.  Once warm it idles OK, but if I pull the dizzy vacuum hose off it dies instantly.  From what I've read this isn't normal -  does this mean it's running lean?  If I plug the tube it will run.

I set the timing like this, and noticed that it seemed to want to run better with the timing even more advanced, but perhaps I just didn't have the engine hot enough (it'd been running for a few minutes, pipes warm, choke flap fully open).  Again though, this makes me think it's running lean. Anyway, timing set to the mark with vacuum disconnected/plugged at about 900rpm.

When cold, setting the initial position by pushing the throttle, the choke flap seems to be in a sensible position for the summer weather, i.e. not fully closed, about 45 degrees.  Should the high idle cam be set to the fastest position initially regardless of temperature/choke position?  Mine isn't, it's hard to see what step it's on but it's low down on the cam, if it's set at all.  If I manually set the choke to the high position it starts up and idles high, after a while idles ok when the throttle is blipped and the speed drops. 

This is all following a carb service so hopefully no issues there, should all be clean inside the carb, I spent time making sure all channels inside where clean/blown through, inlet filter removed/cleaned, service kit with new accelerator pump, gaskets etc fitted.  Mixture screw set to about 3.5 turns out.  When warm, unscrewing beyond 3 turns didn't seem to make any difference.

Things I've checked:
Idle jet.  Unscrewed and checked over again just in case anything had got in there - all clean.
Ignition.  Tested the coil resistances, lead resistances, changed rotor arm (old one measured 15K!), cap looks OK and is newish,  new plugs. 
Air leaks.  New choke pull down, new distributor vacuum advance, new pipes, air cleaner pipe carb inlet blocked off, servo hose replaced with short capped hose to test. 
WD40/carb cleaner squirted round middle of carb, base of carb, vacuum hoses, inlet manifold gasket area - no change in engine speed.
Fuel. Using an electric pump, recently installed, pumping well so hopefully no issues with delivery.

...Calling on the Power Of Club 8090 to instantly provide me with the one simple answer that makes everything alright again.... 

[aec]

Bumping my own post as still having now luck with this, in fact it's getting worse.  

Quick recap:  After 5 years, I'm trying to get this van (1.9DG) up and running again. 2E3 Carb removed, cleaned, overhauled and adjusted this summer.

Van starts OK, and was running OK when fully warmed up, but now seems to have progressively got worse despite me trying to rule out problems.  Now it'll start OK but refuses to idle during warm up and when the choke is fully open.

Things I've already done:
New vacuum advance, new choke pull down unit, new vacuum pipes everywhere, brake servo vacuum pipes and valve tested, even blocked off at manifold, made no difference.
Checked all round base of carb and joints etc with carb cleaner when running looking for leaks - nothing found
Fuel tank drained (again), added 10l of fresh E5 petrol
Fuel delivery is good (electric pump, running ok,) good flow at carb inlet
Coil checks out OK, HT leads all check out OK, new spark plugs.
Timing checked and set with strobe a while ago when it was running Ok when warm
Choke mechanism seems to all look ok.  The automatic choke is set (as it always has been) to the "winter" mark on the body, testing this morning when cold it set the high idle position ok when the throttle is pressed before start up and after running for a few minutes the choke had warmed and was pulling the flap fully open.  

I'm only able to keep it running at a high idle speed (probably around 1500) by manually holding the choke flap about 75% shut and holding the throttle open a bit. Move outside the exact sweet spot with either and it dies.  If I let the choke spring open it will run if I keep the revs nice and high, and seems to run ok, no bad misfiring.

I've unscrewed the idle jet, looks fine, no obvious blockage.  
I've run out of ideas.  Next step will probably be to remove the carb and strip it down again but surely for it to be this bad there must be something else really obvious that I'm missing?   

Any ideas?

[aec]

Took the carb off again today, was wondering if there was a problem with the float valve perhaps sticking or not closing and flooding the carb.  Everything looked fine, all nice and clean inside, no lumps of crud, jets all clean. The float valve seems good with blow/suck test.    When putting it back on I connected the inlet, put a jar under the outlet and operated the fuel pump. After a few seconds of pumping there was a steady flow out of the outlet, so I'm happy that's all good.

Started up from cold, choke was on full. Starts easy, ticks over fine initially with the throttle at the high stop setting.  For a  minute or so it all seems good, I can rev the engine and it settles back down nicely.   Then as soon as the choke opens some more, bang, it's running rough again, instantly stalls, unable to idle.  I got it restarted by forcing the choke flap to the high idle position to give time to dash round to the back without it stalling, but it's much rougher at this point than it is when initially stated from cold.  Pretty soon the choke flap wants to be fully open, but I can only keep it running (roughly) at anything like an idle speed by holding the choke flap almost totally shut and pulling on the throttle a bit. With the choke open it needs revs to keep running.

I've been trawling through loads of old threads here and on other forums and these symptoms come up time and time again but in every case the fix was something I've already checked/replaced.

Totally out of ideas now 

[aec]

Thought I'd come back and update on this one. 

Found a few issues, and I'm not really sure which one has solved the problem, but things seem much better now.

- Checked and reset the hydraulic lifters - engine ran better but no improvement on stalling as the choke came off
- Noticed that although screwing the mixture screw fully in when the engine was warm caused a stall, pulling the lead off the fuel cut off valve made no difference.  The solenoid was clicking and when reassembling I'd watched the plunger move so I knew it was OK. Because the original sealing ring had perished I'd used three stacked o-rings and PTFE tape to make the seal, but because the PTFE made it tight it hadn't seated all the way down.  Fixed this, but weirdly it still behaved the same which I can't explain at all.
- Carb off again, checking everywhere in the idle circuit again.  Poking through all channels where possible and blowing through everything with compressed air.  It was all spotless anyway, but just in case!!  Re-did the solenoid valve using a single turn of gas PTFE tape (thicker) rather than sever turns of water PTFE. Made sure it was fully tightened against the end-stop in the carb body.
- Started to wonder if the Mikuni bike carb jets I'd used to replace the pitted originals are actually behaving differently, the primary jet pre-meters the fuel supply for idle.  This was clutching at straws really, but I was running out of ideas so I swapped back to the originals.
- Checked all round for every possible vacuum leak.  Tested the (new) pull down unit again.  With a bit of plain tube, and a good hard suck, it's working fine, holding vacuum 100%.  But if you just suck gently, it lets air through?!  With the restrictor in place even with a real hard suck I couldn't make it operate, it just pulled air through.  So the new unit I bought appears to be faulty.  For now, I've put in another bit of tube without the restrictor
- Although the manifold, carb and spacer all appear pretty flat and I could find no evidence of any leaks I replaced the two paper gaskets that came with the kit with home made ones using much thicker gasket paper, well greased up.

- Started it up with a much more aggressive mixture setting than I'd previously used - about 6 turns out. 

This kept it running through warm up, but it was rich with black smoke/lumpiness.  When warm I could get it to idle nicely at 950rpm-ish then adjusted in until the revs dropped slightly then backed off 1/2 a turn,   Ended up 4.5 turns out, which was exactly the point the carb had been set to when I stripped it down, and where it had been untouched all the time I've had the van (14 years!)

The idle cut off now works as expected, pull off the connector and the engine stops immediately.

Decided to check the timing again, and noticed that when I pulled the vac off the dizzy the engine speed dropped but it kept running, where previously pulling this off had caused it to die immediately.  So more good signs!  Timing was spot on.

Tried again this morning on a cold engine, everything seems good, but now I've got the opposite - it seems to be running a bit rich on choke - seems like the choke wants to come off a bit sooner really.

But it's good enough for now, and I've got more confidence that I'll eventually make it to the MOT station without breaking down on the way!