Suzuki: 1994 suzuki sidekick, cam shaft, suzuki sidekick

Question
my sidekick runs and idle's fine but when we go to shift into reverse it stalls but goes into drive fine and if your driving down the street stop at driveway put in reverse sometimes it goes in fine other times it stalls why??? just put new cam shaft in with a new head

Answer
There have been shorts involved with reverse (the reverse circuit), as well as shorts that occur when the engine shifts as a result of backing causing the engine/transmission assemply to rotate the opposite direction in response to applied torque forces.