I have a 1999 Ford Mustang. While I drive it will randomly shut itself off and on in an instant and even sometimes the windshield wipers will start turning on randomly. I have changed the alternator and the car battery but i still have no idea what it is. Mechanics dont know what it is because they wait for the engine light to turn on. Any ideas on what it is?

Thanks. Any help is appreciated

 

Sounds like a bad ground cable possable. When your driving the vibrations are causing the wire to loose its ground, killing the car. Could also be a clogged cat ( highly unlikely), or a full problem.

Matthew