Ok i have a 1986 5.0 with TFI ignition. Here is what is happening. I have power to the coil, constant grond at the coil it doesn't pulse with the firing. The ignition module is good. It will run for a few minutes and all of the sudden die, then we check for spark and it has no spark. After it dies the ignition module is warm. If you let it sit for about 4 hours it will fire back up and run then die shortly after. I think it could be the ballist resistor? I'm just thinking about putting a HEI distributor in it but the Proform one I bought doesn't fit. What do guys think?