I am having an issue too (I think) with 1-2 injectors. My car (91 TT) idles ok (slight vibration), but when driving or revving up there is a pa pa pa pa pa @ 2500 RPMS. Having it looked at this week, but not sure if it's an injector or a poor electrical connection. Don't have the money to buy 6 injectors before it's diagnosed. Any thoughts?