Have you contacted APR?

 

I'm going with tweaked on this one.. Sometimes your plugs can even look good and not be. Also if its actually bucking it wouldn't be limp mode. Check your codes again, sometimes misfire codes can get pushed away into the bank and you wont have a check light.. If it was coil's you would have a constant check light that either blinks or under any throttle throws a light.. I wouldn't ask for help on a forum if your just going to tell them they are wrong.. Just my 2 cents though

 

Well, I just wanted to update everyone that gave input and advice on this issue.

My APR ECU programming came with EMCS security lockout - called APR today (a second time) and talked with a great tech name Chris. I explained the symptoms I was experiencing re; engine/fueling cutout at 4000 RPM and general lack of power and boost - Chris indicated that it sounded like my ECU was in "lockout" mode which automatically puts the ECU in program 1 (this is VALET mode on my system).

Sure enough, I used their instructions to "unlock" my ECU program, reset to my 91-octane programming and magically, my A4 is once again the fun, powerful and reliable car that it was back in November.

Great Kudos to the folks at APR - their software and support is great and our Audi's are truly performers.

I did replace my DV, Plugs, Air Filter and MAF Sensor on my A4 - it was all $ well invested.

Thanks again for your help - hope this information helps others if they experience similar issues.
-Cetek

 

Ah, see? All this head-banging could have been prevented with a phone call...

 

I had some similar problems which mostly manifested themselves in sputtering and misfire above 4000 rpm. I changed just about everything (MAF DV Plugs). Then one day the car died completed. It was clearly lack of fuel pressure. I changed the fuel pump. After that the car was back up to full performance. I would take a look at the fuel filter and pump. Looking for a vacuum leak is probably a waste of time.

Good Luck!