no-start problem/99 300m

I have a problem with my 1999 300m. Periodically the motor will die when moving at 25-35 mph. After I stop and re-start it it runs fine. Today, after being started and turned off several times it refused to start. Cranked strong but sounded like no fuel was getting to the motor. Fuel pump tests fine as far as pressure. Ater a couple hours the car started. It''s a 3.5 motor.