dies at stop light

It could be many things, unfortunately and without experiencing the problem first hand or being able to do some basic diagnostic tests its hard to say.First place to start a scan tool will be needed to retrieve codes stored in the computer of your car. The codes stored in the computer would indicate where the problem is or at least give a basic starting point to do tests. It may be ignition, fuel or engine mechanical issues but no way to know without first retrieving the codes stored. Possibly as simple as a vacuum leak or idle control valve not working.

Vacuum hose, check that first