Looking for some pointers on what could be causing this problem, car in question is a 1990 factory big bumper Golf GTi 16v. Car starts fine and goes straight up to 2,000 revs. If you leave it it will slowly drop to 1,000 revs then will waver from 800 - 2,500 revs. Blip the throttle and it responds cleanly, it will sit at 2,500 revs then very slowly drop back down and go back to the wavering (8-2.5) idle. It drives fine and pulls VERY hard all the way to the red line but the exhaust absolutely stinks of petrol. Exhaust is a bit misty too but doesn't seem to be loosing oil or coolant. What could be causing this? I've been suggested so far to look at the idle stabilisation valve (can this be cleaned or fixed?), the water temperature sender and the lambda (does a '90 car run a lambda?). Going to have a good look for air leaks tomorrow too. I'm not sure where any of these sensors are and I'm convinced the Haynes manual is lying to me on their whereabouts! Forgive my ignorance, I'm moving over from Minis and have a pretty steep learning curve.
