A little update on my issue here.
I finally got my cap in today and was able to get it on tonight. So far, it is perfect.
What I did find was this... I noticed that the center portion on the underside of the cap, where the seals are, it was loose. You could freely spin it and actually lift it a very small amount. My old one was frozen in place and would not move around at all.
So I figure that was it, becasue the temp gauge does not get above R even when sitting idle with the heat off.
