Within the side pan of the transmission (drivers side next to front suspension) you will find a "Transmission Control Solenoid".
That vehicle has whats called a lock up torque converter that is controlled by the Transmission Control Solenoid when you get to cursing speed determined by the computer.
Whats happening is that the Transmission Control Solenoid is bad. that Solenoid is locking up the toque converter when it should be released. When you stop at a stop sign or traffic light the car will die. You put the car in park, start it, put it in drive and it dies.
You can pick one up at advanced auto or auto zone for $27-40 with instructions. Don't forget to buy more transmission fluid, these part stores don't sell the gasket for the side pan you will have to go to either a dealer or transmission shop.