2000 Audi S4 Question: check engine and stumble/rough acceleration?

2000 audi s4 ? i started my car when it was raining, but had already driven it beforehand in the rain that day. anyway the car would turn over but had trouble getting it to stay on and idle. after that it would drive but stumbled and vibrated and was never a steady acceleration. check englne light was blinking and or stayed on. then i shut it off, then restarted it and revved it and it went away and drove fine. the next day i started it up and cel was on and kept stumbling.. it will idle fine where it should, but sounds like a v8. is this the coil packs or mass air or ? please help! thanks