I've been having similar issues. I was up to 235 on the highway with the AC on. The thermostat works properly. I was getting boil over into the overflow tank. I replaced the radiator cap and 2 miles later the stock original radiator cracked on top. I replaced with a Griffin aluminum radiator and temps on highway with AC got to around 224. My intake is weirdly set up with the filter sitting right on top of the valve cover. I'm installing a stock one this weekend to hopefully drop that intake air temp. I'm hoping that solved the heat issue.