Had my first coil pack go out on me. It's actually been out for a few days but I thought it was a bad vacuum leak or something. I got a rich code and saw that one of my inline check valves was toast, so I started searching and checking everything. After I made sure about all my vacuum lines I still had stumbling idle and hesitation. Finally got around to unclipping coil packs one at a time to see if anything changed and sure enough, number 4 was dead. Luckily I got connections at some dealerships and got one on the low low. So all in all.... I feel like a real Audi owner now.