1994 Pontiac Sunbird When Warmed up engine stops when brake

No as usual when starting all lights show once started and driving no engine warning lights are on

Forgive the lack of proper terminology here, but am sure I can get my point across. A friend's g/f had the same problem on her car and all it was was the sensor on the transmission wasnt reading the vehicle speed properly, so the car was not shifting down when it should have. When she came to a stop, the car remained in 4th gear, thus stalling out. He verified the problem by disconnecting the sensor and the car ran fine. Not sure what the hazards may be if the car is run without this sensor connected, so would not advise running it too long that way. Hope this works for you.