Just an FYI to bring this issue to a close.
The main cockpit indication of this problem was the temperature gauge giving a normal reading for several seconds and then swinging to the full Hot position regardless of actual temp. It would start without problem when it was cold and had sat for some time. (i.e. over night) Once it had been run, it would not start again, or be very difficult to get started.
Computer did not read anything that would lead to the issue at hand.
I changed the Thermostat and temperature sensor and flushed the cooling system and it was still giving me a "hot reading". After taking it for a short test drive the Expansion tank blew. I had suspected this might be an ET issue. Once I replaced the ET, the problem was solved. While 3 parts were ultimately changed out, I believe that the ET was the cause of this failure. With a "hot" reading, it was shutting the engine down.
All three parts were quite easy to change.
Thank you all, for the input along the way.