I have a 2002 S3 Running stage 2. I started getting what felt like turbo lag and then a day later slight misfire. I was told that coil packs are a common fault and cause misfire so i got 4 new genuine coils and spark pugs. The problem was solved but only for a couple of days The misfire came back. Its now started to use coolant and whilst topping it up half a pint every couple of days notice that i have started getting oil due on the top of the coolant. Hardly any but noticeable. This then lead me to believe the head gasket could be the fault. After finding out the misfire was coming from cylinder 1. I checked the compression in all 4 cylinders and they were all running the same and good compression. The spark plug in cylinder one was dirty compared to the other three which were all as new. I have no over heating problems or and contamination in the oil or any gunk round the oil cap? Could it be a injector or a water cooled oil cooler? The car doesn't misfire bad its only when using the torque or heavy acceleration?
Hopefully you can help