I have a horse that overheats - stopped sweating 2 years ago but have that under control with supplement. 

Hard, heavy breathing after runs for a LONG time....and stays hot to the touch.

I’m about to “retire” this horse from summer runs, but wanted to see if there were any suggestions I may have overlooked!

Deanna Harrison on FB does oils and has for years.  there is a testimony from a girl that her horse wasnt sweating and is now with her oils and she is running barrels.  Maybe she can help! Praying!

This is one of the signs of a "Bleeder".  Try having your horse scoped after a run by a reputable vet.

I’ll have the scope done - adding it to the list today. THANK YOU!

Just read about Cur-ost EQ Cool Down and thought about you. . . 

BioStar makes a supplement that really helped my horse with heat stress. In fact, I just ordered some. It’s called Cool Star EQ and is recommended to cool the body and support the GI tract. It does that, too. My horse had elevated respiration, sour attitude and he was sweating weird sweat patterns. He was miserable. After feeding this he improved sooo much. In fact, after feeding it a while I no longer needed to feed it every day. I fed it 3 or 4 times a week and it still worked. 

I’m in a similar boat as you are, already had breathing addressed, mine sweats but overheats. Next time mine overheats I’m supposed to pull blood for some labs. But I’ve done some research and I’ve found a blanket and leg wraps by coolaid that are supposed to really help with horses like this. I’ve emailed/messaged several people and had very good feedback from them so I’m keeping this on my list of things to try.