does anybody know the reason why my truck does this?

[redshift]

Well the best way is to take off all the wheels and give it a visual inspection. But if removing 4 wheel nuts is too much, then the way to do it is have it upside down on your lap and gently grasp both fronts, then both rears while someone else bumps the throttle slightly with the transmitter. This way you'll be certain all 4 are getting power.