1997 Grand AM stalling

I have a 1997 Grand AM v6 3.1 with automatic transmission. The car stalls and only when it is hot outside it never stalls during the early morning hours or at night. It will stall when the A/C is on but most often it will not stall when the A/C is not on. It has not stalled at speeds above 50mph but on a hot day you can count on it stalling with the A/c on especially after sitting at a traffic light. I changed the fuel filter and yet the problem continues.Most often when it dies I can restart after shutting the ignition off.I have no visible trouble codes and the car seems fine except for the stalling. ANy help is appreciated.