95' GT 5.0 shutting down.

[dave86gt]

First thing you should do is run a EEC system self test to see if any codes are present in either key on engine off, key on engine running or memory codes. If there are no codes I would proceed as if the computer is being told the key is being turned off. That can happend by either a bad ignition cylinder (play that is allowing the rod to move between the cylinder and the electrical portion of the switch) bad switch located on the bottom of the steering column, bad EEC relay (probably under your seat), or wiring into the processor. There are two ways the processor gets battery voltage, one at all times key on or off and ignition key in run mode. If your car is EEC IV most likely pin 1 is hot at all times and 37 and 57 is hot in run. These are the pins you need to carefully check when the engine will not run. Next check the processor grounds, they are typically 20 40 and 60. If the computer has proper power and ground, next is whether the processor is working properly. The processor basically controls spark and fuel. Fuel pressure you should be able to watch and you will really need a scope to see if you are getting spark. But before you do all this, have someone run self test