CEL with immediate hesitation etc etc...

This morning on my way to work my 2002 A4 1.8t (63k) started to hesitate under acceleration (manual trans) and then the CEL came on and started flashing about once a second. The power dropped and I
could hear the exhaust sort of pop a little, like it might be firing only 3 cylinders (?). It started at about the point where the car usually hits its operating temp, if that makes a difference. I use Shell gas primarily and just had the timing belt replaced and the rear seal replaced. I'm the second owner and I know the coil pack was replaced somewhere in the 25k region. When I parked the car there was a definite wet sort of cooking smell, not burning, coming from the exhaust. Didnt smell like coolant. And I could definitely hear something through the exhaust that sounded like a rhythmic muffled clank. Right now she's parked in the paring lot and I am afraid to drive it too much because I know from experience that these problems can get more expensive the more you drive on them. I bought a new set of coils when I got the car thinking that I'd need to replace them, but I didnt since the service tech @ the dealer told me to wait until it started running like crap... is this what he meant? How do I determine if its the coils? Or a knock sensor? or an O2 sensor? ANY advice would be greatly appreciated. Thanks Mike
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Hi, when it goes into limp home mode it feels like it's firing on 3 cylinders, coil packs have a different way of showing they are faulty, believe it or not my first coil pack went 1 month ago at 200,000 <2002 1.8t q>, I was driving along normally and then all of sudden the car started missing when you pulled away, after a day of this missing it then got so bad I could hardly drive it, so thought best to change 1 :)
You need a VAG-com to read the codes, other than that go to a dealer/specialist and ask them to read them for you.
Try changing all 4 coil packs, disconnect the battery leave it off for 5 mins then put it back on, this will usually clear the CEL don't forget the stereo code if you have it.
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