Scirocco GT II Idle problem

[80'sthrowback]

Hi all. I'm new to these forums so please bare with me. I have a 68000 mile Scirocco GT2 with a weber conversion. On cold damp mornings the car starts fine (manual choke) but after I have driven it for 15 miles at 60ish it just won't idle. As soon as I drop the clutch the car just stalls. It starts again straight away but it won't idle and no amount of choke will make it do so. Once I have been in traffic for 5 mins or so its fine (still idles a little low from time to time). The most obvious answer is carb icing but I'm not so sure. I have repaired the vacum pipe in the airbox and that works correctly. I have also disconnected the air pipe so that the carb gets fed with the slightly warmer air from the engine bay. Additionaly, I have tried a different Carb, different distributor, new leads and a replacement carb gasket all to no avail. One final thing to note is that the car doesn't fully warm up until I have driven it the 15 miles and got it into traffic. (heats up quickly then). I have replaced the thermostat but that doesn't seem to have made a difference. Not sure if the temperature issue is related as I have plently of warm air dspite the gauge reading. Anyway I'm out of fresh ideas and I'm wondering if anybody else has seen this before.

[Captain Answer]

This is fairly common by all accounts (mines doing it like a swine some mornings with the original Pierberg carb), have a browse through the help section of the scirocco register forums help section, the links in my signature ;)

[80'sthrowback]

Thanks mate. Will join the register.

[Crasher]

You have carb icing caused by the hot air NOT being fed into the air cleaner by the vacuum operated flap at the intake of the air box. The amount of hot air required is regulated by the vacuum temp valve in the air cleaner and altered by the air flap. Make sure this is all perfect.

[80'sthrowback]

OK Will try. When I first got the car the flap was completely stuck down and didn't work at all. I managed to free it up but It sounds like it might be worth another look. Thanks for your help.