Does anyone know anything about replacing a crank sensor? Or how much it would cost at a garage?

I have been having this issue with my car now for a long time and I never could figure out by myself what the problem might be. It sputters constantly when I drive it and backfires making a loud noise. The check engine light goes on and off. Sometimes its cranks for a while before it will start. The worst problem I have with it though is when I drive it for a while and the motor gets hot its cuts my car off and will not drive again until it cools. This happened the other day and I had to have the car towed back to my house. The man suggested to me that it's probably the crank sensor or the coil packs are going bad on it.