why does my car stall at stop sings

Hello, You are likely having issues with your EGR valve. If it sticks while driving, it can cause the car to stumble at stops, hesitate to accelerate from a stop, or stall at a stop. There may also be an issue with the idle air control valve, or the EVAP system. Scan for codes, or have a parts store do it for free, post them here, and I will give you a better analysis.