The car dies while at a stop why? Does it have to do with the timing belt.

I dont think you have a timing belt! That should be a chain car. 2005 altima's are either 2.5 or 3.5 engines and both those are chain motors. As for your dies at stops, I would assume you have other symptoms associated with it, i.e. check engine light, stumbling or hesitations, overheating, engine noises. The stall out could be related to a lot of problems so what other symptoms do you have?