I have a 2002 Mercury Grand Marquis, 4.6 L. The other day the wife was out and about and after one stop the car would not start. I tried it too. Shifted from P to N, no start. Had it towed home. Checked fuel pressure, 35 PSI with ignition switch to run position, not start. Put ignition switch to start and it started. 5 days later, after being out and about again, numerous starts and stops it will not start again. It turns over buy no start. ?????