Well I finally got to take the Mustang out for a run last night as I had been travelling on business then on vacation for a week and didn't have a chance to drive it until now.
Two weeks ago, I flushed out the rad and refilled it with clean 50/50 coolant then I installed the shroud. While it wasn't very hot yesterday, the engine warmed up normally and operated at a constant temperature. I shut it down for 5 minutes to allow it to heat up a little bit but it cooled right back down to a normal temp as soon as I drove it. I sat at a couple of red lights and there was no change so everything appears normal.
It looks like all is OK.
Thanks for all the suggestions.
Regards,
Wayne