Over heating or not ?

Last sunday i changed the thermostat housing filled up with dexcool antifreeze and ride back home this weekend the car (aveo 2006 100k) oil changed 2000 miles ago , the temperarure gauge went up past half wich has never happened before this happened when i was driving over 55 miles per hour on the highway, got home checked on leaks nothing radiator reserv tank is good ? I add pure dexcool do i need to dilute it? Went to advance autoparts bought a new thermostat and checked codes they told me that throttle sensor is not Sending or receiving good so my question is could this be the cause for the spike on the temperature gauge ? Or could it be something elsethanks for your help

Aveos burp air well, but if it's going just over half it sounds like there could be a bit of trapped air. After topping up, did you idle it for 5 minutes or so with the overflow cap off, and the heater on full? I've never had to raise the front end up, but you could try that as well. AFA the coolant itself, concentrated used at full-strength should have the opposite effect. Just follow the directions on the container.

Thanks I will replace the thermostat anyway the thing that is weird is that just goes a little up on the over 55 miles driving slow in town its regular temperature, will replace the throttle sensor on the weekend if someone has gone thru this greatly appreciate your input thanks