Car stalls when shifting from park to reverse and then won't start when placed back in park

Hello, this does not sound like an alternator problem. If you have an engine light on while the vehicle is running, there may be some trouble codes present in the engine's processor that can help lead you to the source of the problem. If the light is only on when the vehicle stalls, that would be normal and not a sign of stored data. Either way, hands on testing must be performed to see what is going on with your vehicle.