Hey Scott,
This might be it! I didn't think of this until mentioned in previous posts. I once had an old MGA where the batteries sat behind the seats. Everytime, I would go over a bad pothole or bump the engine would cut out. This turned out to be a loose plate in one of the cells which would get moved around in the battery when the car jostled. Sometimes it would break the connection.
I spent a lot of time trying to find a problem in the engine/ignition but forgot about the batteries maybe because they were out of sight behind the seats!

This would be easy to test with the battery out of the car. use a voltmeter and twist the battery.