Sounds like your right there on HSN (1/2 to 1/4 turn out from flush) and LSN (flush) settings. This motor likes to run a little rich on bottom. My Extech .21 seems to run best around 180-195 deg. temps. I guess you could put a dab of shoe goo on outer part of LSN would to keep it from turning. As far as plugs, I like to use ExTech #5 Hot or O.S. P4