Ok this problem has been ongoing for so very long its not even funny i bought a 93 TT and one day after work went to start it and it did but died right away and did that repeadetly i took it to the stealership and they said it was the fuel pump so i fixed that and it did the same thing next thing that happened was that the computer went dead so i send it got it rebuilt and it got back ran a little rough but it worked for a while i let it sit for a while went to start it and the computer was dead again i sent it off to get rebuilt again got it back it ran awesome all night so i park it at my house and go to start it in the morning and poof it starts and dies... back to the beginning i pulled the computer so it wouldnt blow again so now i dont know what it could possibly be all i really know is that it starts and dies no matter what after it sits for a few hours and this can cause the computer to go bad also i think it may have somthing to do with alarm system because itook it to the same dealership a little while before to get the alarm disarmed because i didnt have a clicker and this is from the dealership that told me up front that they had no real idea what they were doing with this car so all in all i dont know what could be doing this and i would really like to know please someone help me out if u can -thanks

 

Try unhooking your ECS computer. It is in the passenger side rear hatch. You will have to take out the "tub" in order to open the door leading to where the computer is. I've heard that a faulty ECS will cause problems with the ECU, and eventually will burn it out.
Also make sure everything else is working properly, spark, fuel, so on and so forth.
Other than that, get a complete wiring diagram, study and start tracing wires. Electrical gremlins can be a nightmare.