You say it gets hotter when you run those high rpm's. What are you taking about temp wise? Also did you pull off the outbound hose water pump to heat exchanger to be sure there is no broken impeller pieces in there? I had that issue and ran hot (190 when 160 is right for my engine). I am also not certain you want to be running max rpm. Everything l learned suggests 80% rpm or a bit more but not 100% except in really adverse or emergency situations. My engine (Universal) will smoke a bit at 90-100% for sure.