When I engage the blade clutch on a GCV160 the engine will bogg down to the point where it will sometimes stall. It usually does not but it almost always does seem close to doing so. What adjustment are needed to make this smoother? I have cleaned the carb and am using fresh gas. Air filter is clean. wondering if governor is not responding quick enough. Does the spring on the throttle butter fly control this somewhat? That spring seems tired. Idle speed with blade off is about 3500 rpm. With the blade on it is about 2900 RPM.