does your cayman have the "standard" midprice monaco layout, ISC engine, rear radiator, charge cooler above the radiator, not sandwiched with it, and engine driven mechanical fan?
That is how our 08 knight is layed out. Our engine temp never varies, sits at 180 always. Double check your guage through the alladin system, but if you got a check engine, it was hot, and that's not normal.
For sure clean the radiator as stated above. I do mine once a year. Without the charge cooler sandwich, the cleaning is pretty easy.
RPM and gear should not be something to even think about. Mr. Allison and Mr. Cummins will put the gear and rpm where they need to be. These systems won't let you lug the engine. I try to keep my foot off the floor going up hill, past a certain point all it does is waste fuel.
