Car will turn off at a red light. Once turned on it runs fine. Please help!?

Car is a '96 Mercury Sable. I just recently put it back on the road not even 3 months ago. I had an e-test and safety done and they both came back clean. Nothing was wrong. But just the other day I was at a red light and it turned off. When I turned it back on the battery and oil light came on. I checked both and they were fine. Could this be a carburetor problem, is it idleing high enough? Or maybe a fuel pump or vac problem? I really need an idea so I don't get dinged at the mechanics cause it never fails when you're a girl.