MY Friend and I have been chasing this problem for 6 months now and we cannot figure out what the problem is. It all started when his fuel pump went bad on him and the Regal hasn't been right since. After the the Engine gets up to operating Temperature the car will not start back up until the car sits for 3-4 hours and sometimes the vehicle will cut off on it's own while driving it. The wiring harness to the ECM had been cut into by the A/C compressor pulley we repaired the broken wires but we are afraid that whatever short had been made has either caused an issue with the ECM or there is another wiring issue. If anyone has had this problem please let me know.