The car that shuts off plymoth sundance 1990

ok I'll bite. Can I ask how your doing this resetting?

Have you given thought your alternator is the trouble? What do your battery volts and connections look like as this happens? What are ALL of your gauges telling you. temp/volts/etc. When the car won;t start, does anything work i.e. headlights, radio, wipers, starter click?

A bad alternator AND a flakey battery connection could do this, based on what you have stated.

Check the ASD relay (poor-man's method is to swap it with a known-good relay, like a headlamp relay, and see if the problem follows the relay).