I'd begin by re-checking the fuel flow rate from the float chamber, in case that problem has returned. If the flow is good, step two is gently moving the governor arm back and forth through its movement range, while looking closely at the linkage and feeling for any rubbing or stickiness. You should also check what the spark plug looks like, in case it is actually running just a bit lean.
Since the hunting seemed to clear up with proper governor adjustment, it sounds as if it is either a marginal problem or an intermittent one. These are the hardest to find. My history is that they are commonly caused by a mild air leak in the intake system, or a stiff diaphragm (fuel pump or metering) that makes fuel control marginal. Remember, you never did establish with any certainty that you don't have a crankcase air leak. You might look for oil around the crankcase and cylinder joints.
