If you have the old style Fuel Injectors it's most likely one of them.. ..Do a balance test if you can or ohm them out. Changed three sets this last month One was on a MINT TT with 58k on it which had 2 bad injectors. Upgraded to the new style using the kit from Z1. The kit is a easy install,, removing the upper plenum is not so easy on a completely stock engine.
Nistune Dealer Built Automatics -ECU socketing ECU eprom upgrades WWW.AAA-HiperformanceAuto.com