If the engine hunts, chances are the mixture is too lean, and that there is some residual gunk in the carburetor. I have had success with using "Gum-Out" or something similar, added to the gas. The engine will have to be started up and run for at least 20 minutes in order for the solvent to clean up the varnish. It is not a good idea to use these cleaners continually, because they might damage plastic or rubber parts in the fuel system, but it should be OK to use a carb cleaner once a year, or so.

Is it possible that there may be water and debris in the fuel system yet? Is there a good flow of fuel to the carb? Verify that the fuel cap is venting too.