Alright, I've been trying to diagnose this issue for a while.
When the car is cold, it idles perfectly fine, but stumbles between 2000-3000 rpm on a part-to-mid throttle acceleration.
I have done the following, in the following order:
New HPFP in January
PCV TSB was applied
Purchased car one month ago at 159,000km:
1. Upgraded coil packs to red tops. - no change
2. Inspected NGK Platinum plugs, wear and gap appeared fine. - no change
3. Performed intake decarbon one week ago, valves were moderately coated (about 2-3mm of coating on each intake) - engine pulls harder at higher RPM, but no change in crossover
4. Replaced cam follower (was showing minor wear)
5. Replaced NGK Platinum with BKR7E Copper Plugs gapped to 0.032" at 159,500km as per - http://www.audizine.com/forum/showthread.php/423881-B7-A4-2-0T-Spark-Plugs-Replacement-Guide-v2-0
- cold start seemed smoother at first, pulled better at higher RPM again, but overall no change.
Tune is 100% stock, engine is 100% stock (aside from copper plugs and red tops)
No CEL's present on the dash, don't have VAG-COM at the moment, but I'm suspecting changeover flaps issue?