Not sure if this applies in your case but had a similar problem with my 99 4.6. Initially it died at a gas station with the anti-theft light flashing. Had it towed to a shop and they said it started just fine. They kept it a few days and said it reported a misfire, and replaced one of the ignition coils. It did not seem to me that this could have been the problem but it did fix an intermittent stutter during acceleration. One week later it started diyng at random even while driving, but would die for only a second or two, since the car was in gear. When idling it would just die. After another week at the shop they found it was a broken wire in the wiring harness under the battery tray. Had to do with broken communication between the ECM and the instrument panel which does the anti theft key validation.