2003 Sable dies unexpectedly

2003 Mercury sable 3 liter standard engine. Quits while driving, radio snaps off, warning lights go on dash, headlights go out, engine dies, usally clears up in a few seconds. If it is stopped already, or idling in line, it dies completely, will start immediately back up. Dealer has replaced ignition switch two times now, a noise developed and cam sensor was replaced. The car continues to die on its own. It happens occasionaly not constantly or regularly, have noticed it stopping when damp weather. Once while sitting listening to radio in rain, engine off, turned on wipers, radio snaped off dash lights came on then cleared up. Now has 50,000 mi. Has done this since about 25,000 mi. Thanks for ideas.
added:
The car runs fine except for the unexpected quits. It makes it uneasy to depend on. After the first ignition switch it did fine for several months, then again they suspected same switch and replaced again, this time it wasn't long to do again. Again all electrical quits when it happens particularly the radio snaps, then all dash warning lights come on, if moving it catches quick enough to still run, if almost stopped or completely stopped it will die, but has always restarted like nothing is wrong. Yes I am willing to check what you suggest Thanks again