I've got a problem with my '83 T25. This first presented on a long motorway trip soon after I'd brought it - After a particularly long grinding uphill stretch I hit a roundabout and took my foot off the throttle to brake and the engine cut out. Basically, it will not idle. If some pressure is on the accelerator it will keep going but if I try and change gear, coming completely off the pedal, it cuts out and the battery and oil lights come on (battery flickers and comes on first). I had it looked at a local garage on the trip and the guy in there tweaked the linkage to the accelerator arm (sorry don't know the correct names of these bits) and it seemed to up the revs and keep the engine running - if a bit frantically - when left to idle. He told me to have the twin carburettors looked at when I got back home. So, I took to my local garage and told them the problem and got the carbs serviced - new gasket seals - and it seemed to be ok. However... I've done some 40-60 mile trips in it since without incident until today. Did 60 miles motorway yesterday - may have been pushing it as was in a hurry (topping out at 70mph!) - and when I came to drive it this morning the problem was back. First seemed a bit juddery or chuggy and then first roundabout I hit, cut-out, battery and oil lights on and had to restart. I drove it the 60 miles home on the motorway but issue still present when back in town and hitting traffic-lights etc.
Anybody got suggestions as to what it might be?
And - as an aside - is there any retro-fit in-motion heating system for these vans - I'm freezing my toes off and the 3 levers do beggar all to clear the windscreen or breathe any relief in to the cab. Have taken to driving with gloves on (dual purpose - warmth and screen-wiping) and a granny-blanket over my lap, like some Victorian Hansom Cab driver.

All the best and thanks for any help - Chrubble.