1994 Mazda 626 runs good,dies but restarts

had lots of work done new fuel filter,spark plugs and wires,rotor and cap,oilchange and new belts, still would run fine but die once in a while like some one shut the car off, took it back to the shop and they said ign. module which ment a new distrbutor at $400 had that done left the shop went 4 miles and it did the same thing, if i turn the key off after it dies it will start right back up most times but has once or twice had to wait a few minutes,just don't know what the next step is...thank you