All, Two weeks ago the Mustang began to shutdown on the highway. A few years ago this happened and I changed the TFI and everything was fine. I figured the TFI must have went bad again. I changed the TFI. Went down the road and the car shutoff. Towed the car home. Figured the TFI couldn't be bad becuase it was new. I then changed the PIP sensor to rule that out and I also changed the coil as they were original. Car started and shut off after about 10 minutes. Traced from the coil to the distributor with the test light. Pointed to a bad TFI. Put in an old bad Ford TFI that I had and the car started right up. Figured I must have purchased a bad TFI. Went back returned the TFI and then bought a Ford TFI. Figured the after market was not good. Put the new TFI in yesterday, took a short test drive about 10minutes, came home as I was parking the car shut off and wouldn't start. Immediately put an old Ford TFI in and the car started right back up. My Mustang is a stock 1987 5.0 Automatic an is my daily driver. 123k miles. Any Idea? The car is in great shape. Seems like the TFI is getting too hot too fast. I can't imagine I have purchsed two bad TFIs. Once it is cool i will start.