When you have a broken motor mount, it is not noticeable by checking the throttle linkage while the truck is sitting still. The throttle linkage will seem just fine, along with everything else. It only jams when the motor moves and releases once the torque is gone. I would strongly suggest checking the motor mounts by c-a-r-e-f-u-l-l-y and slowly jacking up the engine. Use a wooden block to spread the load. Observe the motor mount. If the mount separates as the motor rises, guess what? Broken mount. Cheap, and relatively easy to fix on the 22 motors.

Richard S.
88 Toy 4x4 Truck, 22RE, 3"BL, 5-Speed, Muds
Proud to be an American. Blessed to be a Texan!