Dick, I doubt seriously your oil content is going to affect how it runs - very doubtful it might cause surging.

Full throttle is very easily tuned. No different than a glow engine - unless you're trying to do it with the cowl on. If that's the case, take it off and leave it off until the engine is running right - on the ground and in the air. You can see what you're doing and you eliminate the potential for overheating. You can also see if it's sucking air....

Regarding the way the engine is running during your landings, leaner settings generally make for trouble. Rich engines are happy and reliable. If you're struggling with the way you're doing it now, maybe try something a hair richer - even if you feel it's not running as smoothly.