I have an 89 3.0L Auto tranny that runs like a Swiss watch for 50 miles today, 30 miles next time, but dies. After it dies, it will turn over but there is no spark. Sounded like a coil opening up to me because it will start after it cools down completely. I've replaced the coil twice, the plug and coil wires, distributor, cap and rotor, and engine relay. I'm starting to think it is the ECU. Any help would be appreciated. Another symptom might be that the tach is very irradic when it is about to die.
Thank you.