Hunting/Stalling/Rough Idle and Knocking

[RCN]

1990, 1.9L DG Petrol, Automatic, LHD [New(ish) engine in feb from a syncro]

Some advice please.
When we left the campsite today the van was idling nicely and drove away fine for about 2 miles. At that time i felt a slight miss or stalling going on and it didn't get better. at the T- junction it stalled, but fired right back up and i was able to carry on.
When i sped up i think it went away briefly but came back again and had to use neutral to keep the revs up. when i was able to pull over i kept it running, but without some throttle, it would died straight off, other wise it would run but was hunting (revs continually going up and down). After about 5 min or so i carried on and it seemed OK for another 8 miles until it started again, but not for long but it never died on me.
(just remembered- the 1st and 2nd times i was on a straight stretch of road, but in-between was a winding B road)
Get home, and while backing up into my spot it starts hunting again, but didn't stall.

Engine lid off and i check the following:
fuel filter- looks new and clear with a light shining through-but will get a new one as it's about 2-3 years old i think
vacuum hoses- were all replaced in the spring, all there all tight
removed and tested idle stop solenoid- works fine
dizzy cap and rotor- rotor looks a bit old but OK, will get a new one anyway
Little fuel screen in the carb where the feed line joins- a couple of very small specks, but nothing that would cause this. Cleaned and replaced
Ign coil-cold to the touch
fuel pump- cold to the touch, took off hose and cranked engine, good amt of fuel pumping through. have a good 2nd one so i might swap to see what happens any ways

I did note that the fuel from the carb at idle was not a nice steady flow (the reason for the hunting). I sprayed around the carb with some WD-40 to see if there might be a small vacuum leak, but the engine never altered.
I seem to recall the old engine doing this to me a few times, so i don't think it is the engine itself at fault

The knocking has always been there and when i used a long screwdriver to listen it sounds like the fuel pump- or at least that's where the sound is loudest. but at its base it's quite. but like i said it was pumping what looked like a good amt, but will swap it to see if the knocking goes away.

Can't think of anything else that stood out, but better to give as much information as i can to help any reader.
Cheers.

[marlinowner]

Could it be water in the petrol? If it changes between straight and bendy roads, could be something in the bottom of the tank.

[RCN]

i would have thought that on bendy roads the fuel is being thrown around more so then a straight stretch, so it would cause problems then. It has 3/4 of a tank so i'm not sucking sludge from the bottom either ( i hope)
i had it on the drive running for the longest time and it would hunt.

[RCN]

Could it be water in the petrol? If it changes between straight and bendy roads, could be something in the bottom of the tank.

What do we use over here in the Uk for water in the fuel? In Canada we basicly use methal hydrate. 50ml in the tank will evaporate any water or hoar frost that collects on the inside
anything like that here? Couldn't hurt.

[RCN]

Update: Changed the fuel filter- had some bits in there so good to change that,took the top of the carb off to get to the float bowl and found some crusty stuff in the bottom. had to use a screwdriver to help break it up to wipe it out.
the other pump won't fit because the top pipe faces directly into the oil breather tower-stupid design.
started it up and runs just fine, no hunting, idles like a dream. hopefully all fixed...until the next time