Stiff throttle control opposite of throttle creep - too tight!

[ole blue cobalt]

I bought a new volvo side mount controller and everything was working great until this past week when I trailed the boat on some very bouncy roads. Now when it's in gear, both forward and reverse throttle is extremely stiff. Once in neutral, I can rev the motor and the throttle is smooth as silk.

I believe that somehow the friction control tightend on the bumpy roads! Am I crazy, anybody had this problem? How to fix?