Having issues with my 16hp Kawasaki Fh480 V KAI Engine... It is reving up and down at all rpms, the throttle linkage that conects to the carb and to the bottom of the carb is mowing up and down when it revs, if you hold the linkage in place it will stall out.. whats causing this? i took the jet out and there is no debris in it. I took the fuel pump apart all looks good.. whats the issue i need a quick fix soon i mow right after labor day HELP!!!