Put the truck on a stand and keep the transmitter off but turn on the reciever and move the servo wires and battery wires and see if the servos twitch. If there is twitching, use heat shrink tubing around the wires to help insulate from interference. This happened to my Nemesis, the battery wire was causing interference with the throttle servo and it would lock at wot. Somtimes it could be a simple thing as a couple of wires being to close together or if the wires are close to a metal component such as the throttle or brake linkage..I hope this is some help.