1993 Nissan Altima Possible Problem

My car has been shutting off for the past two going on three weeks & no one can find the problem because by the time I get it to a mechanic; the car starts right back up; just as if I am driving the car will shut down & start right back up within 1 minute (if that). The check engine light comes on but goes right back off & by the time I get it to a mechanical shop it starts right up & runs normal. It doesn't even shut off if it's running for a long time but when you drive not even 5-10 maybe even 20 miles; it will shut off. It just passed inspection & nothing was found to be wrong. I know it's electrical but could possibly tell me what part may be going or what's going on with the car?