I have a 1990 TT with 85000 miles. I just rebuilt the engine and upgraded several components. It is my understanding that the injectors have a high rate of failure. More like not if they will fail but when will they fail! I actually lost an injector right before I started the rebuild. And I think the word is the transmissions have issues. Mine actually grind a little when down shifting from 5th to 4th until I replaced the fluid with Redline MT90. I am sure that there are a lot more knowledgeable people on this forum that can provide detailed information. Good luck