95' GT 5.0 shutting down.

[Rod Miles]

Hey Guys,
What a great board you guys have here! Maybe someone can help me. I have a 95' mustang GT 5.0 with the T-5, 5 speed. Mods that have been done is under-drive pulleys, fresh air tube W/K&N filter, 373 gears, flowmaster mufflers and a pro 5.0 shifter.

Some times while driving the car it will shut down, the tach drops off to "0" rpm's just as if the key was turned off. Some times it will restart right away some times it takes a couple of hours.
It has gone weeks with no problems and then some days it may shut down 5 times within an hour......

You can hear the fuel pump kick on and then off when it has built the pressure. I have noticed when it is ready to start you can turn the key to the position just before it kicks in the starter and the tach will jump up to around the 750 rpm mark. If it's not ready to start the tach will not move or goes down toward the "0" rpm mark.

So far I have replaced: the ignition module, coil, alternator, battery, plugs, plug wires, dist. cap.

As stated it has no set pattern to these shut downs so this is kicking my butt..........

Could this be the computer, key switch, O2 sensors, distributor??????? Help!!!

Thank you!!
Rod Miles