i have a hustler z and love it so far! one problem i have is the kawasaki 23hp engine started surging at about 40 hours. The local dealer cleaned and eventually replaced the carb. problem was fixed, or so I thought. Now I have to engauge blades at full throttle or the engine will die. I don't want to have to continue full throttle engaugments of the blades because it's hard on the clutch. Any ideas??