86 Ford Mustang

This Mustang does not have an alarm system factory or aftermarket I have changed many things to get this car to run with no luck I changed fuel relay and checked pressure and has the correct fuel pressure for the injection system, changed ignition switch, ignition control module, Ignition coil, have not changed starter relay or starter is it possible that the starter relay could be causing this problem and is there any way to bypass this relay to get this car to run
the car sat for a year or so when I got it home was looking it over I found the fuel pump relay was missing and at that point we did not have fuel pressure and would crank but not fire when I replaced the relay it had pressure and was working with the proper fuel pressure and would run in the start position but when the key was released to the run position it dies, Is there some area that I am overlooking?? ? :)

Mustang 91 2.3 auto
Same problem - runs only when the key is in start position when released to the run position it stops - ignition switch and ignition control module replaced -
still no good - where now?