Adjust the linkages themselves if this is the case. Clutch engagement - pick the truck up off the ground as it rolls by you slowly (before you break to a complete stop), or start it, let it warm up and pick it up, if the wheels spin the clutch is engaged or trying to engage at idle rpm, idle may be a bit too high. I'm thinking its probably not this but its easy to check. Once warm you can get the idle pretty low, may have to use some throttle trim to start it though.