big problem!!
 

i have an 88 gt just took out motor and forget where one wire goes behind the upper intake its red heat coated and has an eye on it anyone know where it goes??

also need an vacuum diagram ??

wire
 

Ground?

second vote for ground

It IS a ground and an important one! That is the ground wire for the injector harness. Without it yopu will have a lot of "backfeed" problems with the EEC and the engine will not run right as the injectors "ground " themselves elsewere at the detriment of some other component. That wire gets hooked up to the back intake manifold bolt on the drivers side, the one with the "post" or "stud" sticking up from the bolt head.