My 2005 Excursion with a 350 Cat C7 has handled 105F just fine so far, but I clean my radiator and inter-cooler once a year. When was the last time you cleaned yours? Check for any scrap paper, plastic grocery bags or other junk also that could have gotten sucked up in there also.
Also, I really like my Scan Gauge ($150 on Amazon) I have mine set to to the engine temp, oil temp, air intake temp and something else. The SD engine temp is a lot more accurate than your MH's gauge and the MH probably doesn't have an oil temp gauge or air intake gauge. When you see the air intake temps going up, then the engine temp could start going up also.
Bill
