2007 GT loss of power?

Hey so I have a 2007 GT with the 4.6 3V manual and it got pretty hot and has overheated a bit at the “H” but never boiled over. I flushed the radiator, replaced the thermostat with a 180f and fan+plus all the wiring that melted back, it kinda fixed the overheating not really, it’s still will overheat but it takes longer and it doesn’t at hwy speeds. Also there is a noticeable difference in power, really dog in 5th on the freeway, definitely isn’t holding speed very well but it does.

The coolant looks good, not chocolate’y. No white smoke out the back. No coolant leaking.

My next plan was to maybe replace the radiator but that wouldn’t explain the loss of power.

Any advice from someone that had this issue or knowledge that would be greatly appreciated 🙏.