Why does my car die when it idols or when come to a stop. If I don't give it gas

There could be several things going wrong here. First - Have you disconnected the battery recently? If the answer is yes then the ECM that stores system settings has lost the "idle" function and the car must be taken to a garage to go through what is called an "Idle Learn" process with a T1 diagnostic tool. There is no way to set the idle by hand. Second - You may have a faulty Idle Air Control Valve but you should have received a lit engine repair light but not always. The Idle Air Control sensor is mounted on the Throttle Body and is easily accessible. Disconnect the connector plug, remove 2 Torx screws and pull the sensor out to replace it. This condition could also be caused by a faulty Camshaft Positioning Sensor.