Truck stalls when put in reverse?

Auto or manual transmission? The reverse gear is very low, lower than first gear, so it does take a well-tuned engine to prevent stalling - it takes strong accurate firing to generate the torque necessary to turn these low gears. If you have a manual transmission, you might have to rev the engine to generate the torque and then shift into reverse. If you have an automatic tranny, you will have to service the engine (tune it up) because you don't have enough control over the shift mechanism to rev it and slam it into reverse w/o damage to the transmission. You should also do a compression test - weak rings or other problems with compression will lower the torque. The problem is worse in cold damp weather because a cold engine does not fire as efficiently as a hot one.

i do not recognize how a lot help that this may be, yet you could verify and word in case your motor is getting the right volume of gasoline, and verify the ignition equipment, perhaps you've a fouled plug, or undesirable wires. i wish that this may help you.

could be many things check your idle.