CARB ICING on GT5S (Weber fitted)

[knobstar]

OK guys n gals - I'm bricking it! I've got to drive from Bath to Bradford at 3.30 this afternoon and I think the Audi's got a serious case of carb icing. Or atleast I think she has!

Got nearly all the way home to Bristol from Bath yesterday (13 miles with a nice bit of dual carriageway in the middle) and it starts to stutter after the dual carriageway. Worse on part-throttle (could rev the nuts off it with no load and second butterfly opening), eventually dying completely even with my foot to the floor. Left her a bit, say, 5 mins, then restarted and away we went again - presumably when the ice had melted

Same again this morning but in reverse (coming to work) apart from I didn't have the time to stop so had to drive her mostly on full throttle, slipping the clutch like mad with a good dose of bunny-hopping in there too - looked like a right tool.

Question is - how do I sort it? She seems to be running very cool at the moment and takes ages to get a good stabilised idle. I put a u-tube of piping on the inlet and outlet of the inlet manifold where it used to connect to the auto-choke on the pierberg and that's not leaking. I don't know about the hedgehog heater thing although its connections (power) seem positive enough. The only questionable item for me is the vacuum-operated(?) preheat pipe valve/diaphragm thing as it's a bit gunged up - can I just bypass this permanently by stabbing the (what feels like) camera film so as hot air is let through all the time? Can I blank off some of the radiator with cardboard or summat such that she runs hotter and hence de-ices btter due to hotter coolant?!?

PLEAAAAAAAAAASE HEEEEEEEEEEEEEEEEEEEEEEEEEELP!!!!!!!!!!!!!!!!!