Engine stopping

My mother recently bought a used '95 320E from an otherwise reputable dealer here in Arkansas. A few months later, she's experienced the car completely stopping on her as the car's stopped for a red light--both in the morning after being started for approx. 10 min. & now anytime.

The 'check engine' light now stays on, she's said.

Naturally, I'm very uncomfortable with here driving and still having this problem even though she's returned the car & the service dept contends that they're not finding the source of the problem. We're taking it to the shop on next Thurs.

Anybody have ANY possible suggestions to direct these service people? Or any suggestions.

ALong