why does the car act like it's going to die at a stop light?

Hello, there are multiple reasons an engine could want to stall when stopped. There could be a fuel or spark issue, there could be an air intake issue, there could be a vacuum leak. In any case, you'll need a proper diagnosis by a local technician to help determine what is going wrong. Here are some folks near you to contact - click the link: http://repairpal.com/mercury-within-10-miles-of-lillian-alabama-36549