I have a used TT 2002 1.8T 2wd
runs good for about 20-30 miles but performance degrades until un drivable over time. Bucks and occasionally throws a P0171 lean code have vag-com reader tells me nothing is wrong. new coil pacs, plugs, MAF sensor, air and fuel filter. seems to be heat related, the longer it sits and cools the better it gets so wash rinse repeat every day.

Lots of black soot in exhaust and occasionally backfires when running bad