Ok, the fix is in! I talked to my buddy at Walnut Ridge RV service in New Castle, IN just a few miles from my home.
He had heard of this problem with some other units in the past. Turns out, Atwood is the only manufacturer who puts a "mixing valve" in the plumbing. They don't do it anymore, but the one I have, has this device. It is used to heat the water to a higher temp, then add cold as it is dispensed. Well, when it malfunctions, it just adds too much cold!
Now, you may disagree, but I have removed this device. I do not have one in my B & M home, and since other makers don't use it and Atwood doesn't either, I can add my own cold water to get the temp correct.
Thanks again, for all your ideas. Good ones, I agree, just something else this time. David