OK, I replaced the coolant temperature sensor the other day. The first start up seemed a bit funny (hi RPM's), but then it kicked down and now seems ok. It has gotten a bit warmer here the last few days (upper 50's), so now I must wait until the cold air sets in again. This weekend it's going to drop into the 30's at night so that will be a good test! For now it's seems OK!
We shall see!