New to site, new to Mopar overheating issues

I must ask, do you know for sure how warm it is getting? Replace the cap if you can't have it tested.

I don't and I must have gotten rid of my temp gun because I can't locate it.

So the two times it got really hot on the dash gauge is when I was driving it back after I got it, mostly interstate, and when the wife and I took it into town. Typical stop light stuff, but open road as well, even though we were doing 60 the temp keep going up. It will run between half up the gauge to 3/4, then start to climb to the H. The dash and everything still has the stock look and looks really nice, so I hate to hang aftermarket gauges. The suspect part to me was it stayed steady mostly then continued to rise.
I'll see if I can borrow a gun possibly.