Car shuts down;all power. random

1996 Mercury Grand Marquis LS, 183000 miles. Car loses all power, randomly. Then starts up in about 3 seconds.

The following repairs have been done: crank sensor, cam sensor, idle control valve, ignition switch, all ground wires checked. There are no computer codes generated. This has been going on for over a year. Has been checked by dealer and three other mechanics.

All power shuts off? Dash goes dead, radio off, etc?

If so, this has nothing to do with the sensors you changed. Most likely culprit is still the ignition switch. With the car running, jiggle the key around.

How many keys are on your keyring?

Check also the power cable to the main fusebox. That may require some dis-assembly.

My Mbz 300E was randomly dying along the road for about a year. After a short time it would start up with no problems. It turned out the power supply to the (main?) computer was dying. When it finally died for good and was replaced, the problems stopped.