Engine/Trans Temps High Again

[Gary M]

09 Knight 38PKQ 360 Cummins 

After a month of being sick(Covid) we decided to head south to our winter hangout. Before getting sick I had the coach serviced. Motor, Genny, radiator steam cleaned. They also without telling me did an ECM upgrade they said was needed. On our first leg from Twin Falls, ID to Nephi, UT, temps were running higher than I thought they should for being 75 out and flat landscape (199-205+). 6th gear, 1700 rpm. I tried dropping into 5th at 2100 rpm and temps dropped sometimes to183 but ran about 188 which has been normal for my coach. So I was jockeying back and forth to keep temps down. Still have two days, 9hrs to go. Outside temps mid 80’s till i get there which is good. 
Oh and since the service my MPG has dropped from 7.7 to 6.5 ????
Appreciate any suggestions on temps and MPG change. Pic is after I dropped to fifth an temps started dropping.

[miacasa_2000]

I'd look long and hard into that ECM upgrade. Cummins will give you the correct parameters that you can take to a shop and have yours checked and or recalibrated to the proper specs. At least you would know.

Roy  2003 Dynasty   

[Gary M]

3 hours ago, miacasa_2000 said:

I'd look long and hard into that ECM upgrade. Cummins will give you the correct parameters that you can take to a shop and have yours checked and or recalibrated to the proper specs. At least you would know.

Roy  2003 Dynasty   

Cummins in Idaho actually did the upgrade.