I need some help with my 89 t2 s5 . The problem is that I have a new motor built by one of the best. The problem is it hauls *** in town but when I hit the highway and go for about 3miles at a constant rpm( cruise control) it will start to hesitate and loses all power and eventuly will die. If I let it cool down for about 10 mins then it will start and run great again but it will start up again. know it wont even make it around town anymore. Have replaced : computer, wiring harness, both coils, tps's, mass air flow, grounded the engine bay to help it, have checked all the ecu pins and everything checks out all volts correct everythings fine, no vaccuum leaks, fuel pressure is great, have replaced the injectors, compression is good when it is acting up, can't find it!!!!!!!!!!!!! PLEASE send my any idea's need help. No one knows what it could be.

 

try posting in the 2nd generation specific category. you will get a better response there.