Sounds like its running too lean. Try richening the HSN up a bit and see if that helps. Be patient as each adjustment can take a few minutes to show any effects. If you have no luck and it keeps on doing it, then its possible you have an airleak somewhere causing the lean mixture. Bubbles in the fuel like most likely indicates an air leak somewhere.

In terms of the gears shearing, its not so much the truck itself but simply the gear mesh between the CB and the spur. You'll need to adjust that so there is not one hint of a binding. Put a piece of paper in between the CB & spur, which should help set the right amount of play. You should be able to remove the paper without tearing.