I've had several misfires before that I managed to fix but this is insane. Sorry to post a new thread again on this issue, but nobody has replied...
I drive a 2001 A6 2.7t(currently running stock progamming since this issue).I've been having on and off misfire issues for about a month. I checked all the usual stuff, plugs, coils, ICM's etc..I had a new motor put in about 6 months ago that had a diff model MAF, so I had to go with it. I kept getting an epc light, and a MAf related code every now and again,but the car ran fine up until about a month ago. Cleaned the maf with no luck. I bought a used one that was the identical model, from a car that had no codes and a working MAF. I put the used MAF in, and I got the ESP and ABS lights, just like running with no MAF at all. I returned it and just got a brand new one. I also changed the connector housing and re-pined it because it was worn. I just installed the new MAF after disconnecting the battery for about 1 min, hoping this would reset and clear any codes. I left the ignition on for about 4 min or so because from what I read, this will reset the throttle position. The car starts up now(before with the old maf, it wouldnt even run with it plugged in) but I still get the ESP and ABS lights as if its running without a MAF and its still running like crap. The rpm's needle also jumps everytime I let off the gas after revving the engine, also like running it with no MAF. I have an 02 sensor(front passenger side I think) thats been showing up on scan's, could it be causing this? Even if it is, why would a new MAF not be working? This car is my daily driver and I dont want to fry my cat's.

 

Check the for vacuum leaks(they'll crack with time) and check your purge valve.