Why is my car stalling when i put it into reverse?

This is just a recent problem that has never happened before. Now when i try to reverse, sometimes, not always, the truck starts to hesitate like it's going to stall, if i put it back into drive it stops hesitating however if i dont the truck stalls on me. I can start it back up with minimal problems, like i have to rev the engine to get it to start but then it starts no problem.