Car stalling problem



I have 1996 Toyota Camry with 83,000 miles. I have a stalling problem that seems to happen when I am driving slowly (around 30 mph) in traffic. The car starts to stall, starts to shake a bit, and then it turns off. This happens in about 2-3 mins. When I restart the car, it runs fine. My mechanic can’t find anything wrong. It’s a little scary when this happens in traffic. So I’d appreciate any suggestions. Thanks