I have an A3 1.8T (01)(AUM engine) with the following problem.. When I first start the car in the mornings especially when its cold and wet, the car runs very poorly. When idoling the revs don`t stay constant and the needle jumps up and down, sometimes the car will stall (rarely) to get round this I keep the revs up manually by holding down the throttle a little. Once the car warms up then the problem is pretty much unnoticeable except when you come to junctions you can sometimes feel it again.
Been to the garage about it a number of times, there have been various fault codes, which we dealt with, Temp Sensor - changed, MAF has been changed - no fault code. The fault code I keep getting now is "Random Misfire" which occurs when the idol drops and the car is about to stall.
The car has a Hyperboost DV and I have changed the Waste Valve in the past aswell. It had new spark plugs about 20K ago.