When i put truck in reverse it dies

Which engine? What have you done for maintenance? Last time spark plugs replaced? Only when cold or happens when warm too?

Always start with the simple stuff.. look for vacuum leaks. look at accel cable attached to the throttle body.. is it stuck holding the throttle plate open? The big Vac hose from the intake manifold to the brake booster? . remove the big air hose from the airfilter to the throttle body check the throttle plate.. and clean the mass air.. special spray cleaner at auto parts store. Did this just happen or did you change something.. DID YOU INSTALL THE TPS WITH THE HOSE ON AND COULD NOT SEE THE THROTTLE PLATE POSITION?.

the throttle positions switch could be out of adjustment making it pick up engine rpms when you put it into gear from park to reverse .had this happen once took it to shop and they adjusted the throttle position sensor and it fixed it .hope this helps

Best Manuals here's link to get you solution for the problem in your vehicle

There is no idle adjustment. That is controlled by the computer via the idle air solenoid. You can try cleaning the throttle body though. In fuel injected engines the throttle plate gets gummed up where in older cars it was kept clean by the gasoline flowing through it. Use any name brand carb cleaner that is marked "sensor safe" and spray around the perimeter of the throttle plate and also do that while running. After cleaning, it should run better. You can also clean off the cross wires inside the bore of the mass air flow sensor using a q tip and the same carb cleaner. Gunk buildup on the wires changes the way the sensor reads air flow.
Any questions about anything you don't understand, just ask.

If it will start right back up and if you hold gas pedal will truck stay running ? if it will stay running when you hold the gas then replace the idle air control valve it is bad and cleaning it didnt help. but if it wont stay running even if you hold the gas pedal then the first thing is to make sure you are not loosing fuel presure

It sounds to me like you have an internal vacuum leak in your transmission.

it could possibly be a bad throttle position sensor

Check the throttle position sensor.

Check the crankshaft position sensor. If the plug is loose or the sensor itself is bad it will cause similar problems