Well I don’t think I have any leaks I pulled a vacuum on the system to fill it and let it sit for 15 minutes or so and had no signs of the system leaking down, I flushed every part of the cooling system each individually until I had clean water coming out of everything. I personally do not use any rtv on the thermostat housing I only use the paper gasket, and the thermostat is a murray brand and I have not had a issue with them in my other jeeps, not to say that this one isn’t bad out of the box, but I think I’m going to start by cracking the cooling temp sensor and making sure I don’t have a air pocket like suggested above. Also to note the gauge did not fluctuate before I redid the system, which I only did due to previous owner filling system with water only and it was all rusty looking crud in there and the coolant pressure tank had a crack in it, and I was having issues with starting to overheat when sitting at a light and it would be fine as long as I was driving.