How do I stop my Kohler Command Engine from governor hunting at full throt?

I have aCV25 Spec.#69534 Kohler Command Engine I recently overhauled for a friend the engine starts instantly and idles smoothly and accelerates to wide open but as I move the throttle off idle it starts to slowly hunts up&down.I took the Nikki Carburetor apart and sprayed out the passages out and used compressed air to blow out all passages. The float needle observed with a magnifying glass. I also removed the welch plug to gain access to the idle screw also removed and cleaned out and reinstalled,it was set at (1) turn out,it seemed to run best at that setting.Could the Solenoid shutoff valve be the blame?