It sounds like your engine is not getting enough fuel.
not downshifting.
You Are Putting To Much Load On Your Engine. When It Starts To Stall Drop It Into Regular Drive. Also You Need To Drive At Slow Speeds In Regular Drive. At Speeds Say Around 50 MPH You Can Use OD. By Allowing Your Car To Slug Around In Overdrive You Are Doing Your Transmission In Amoung Other Things. Your Car Was Not Designed To Run This Way. Stay Out Of Overdrive At Slow Speeds. This Should Solve Your Problem. If This Does`nt Have A Good Tune UP.
sounds like a crankshaft positioning sensor. must be at low speeds and stop signs?
It would depend on what you call low speeds.
If the oil is low in your car, it can eventually cause your car to stall and not start. It can also kill your engine.
Is it low on Anti-Freeze? That is a known issue for a car to stall!
because it's low on gas.
You may find helpful information here: http://wiki.answers.com/Q/Why_would_a_car_stall_when_idling_at_a_stop_light
If the car is starving for fuel or air (low power at idle), the car will stall while turning.
Only if it's so low that the bearings ovrheat and sieze the engine.
Squeking at low speeds? Its your coil springs in your suspension. Have them fixed and the problem should be solved.
The stall speed is classified so it's not publicly available. But it is incredibly low - less than 100 mph.