Stalling problem

Hey guys, not sure if anyone can help or knows whats going on but for the first time today I turned my car on, it was hot and in the sun and after I turned it on I turned the AC on and the car stalled. This has never happened before but I do know that usually when I turn the AC on the RPM's do drop but usually just bounce back up. I also have some hesitation when I first start the car sometimes but it usually just hesitates for a second then goes and is fine after that but one time it hesitated then stalled. Im not sure if these issues are related to the same problem but if anyone has any ideas why this is happening let me know, help is greatly appreciated, thanks :confused: