Overheat/lack of power

Last night my 2000 Explorer, 4.0 SOHC, auto overheated in 39C weather. It only hit red on the temp gauge for a couple of seconds then the engine pretty much lost it's power. The tranny also started shifting very funny and kicked up gears very quickly, like it was trying to save any heavy loads on it.
I let it cool for a few hours then started it up again. It had full power and the transmission shifted fine until it got hot again. My oil level and colour is fine, my transmission fluid looks fine but my coolant level was a touch low (could still see it in the rad but nothing was in the reservoir).

What happened?
What can I do to troubleshoot this?

Thanks in advance.

Start by running your truck till it gets to normal running temp open the hood feel the top radiator hose see if its hot or not you may have a problem with your thermostat sticking , also check and make sure your fans spinning when its supposed to i had a problem with my fan clutch and the fan wouldnt spin causing over heating

Does the 2000 Explorer have some sort of limp home mode for the engine and tranny? It lost most of it's power and the tranny started shifting very strangely.

Thanks

it's called fmem.failure mode effects management.sounds
like two differnt concerns trans slips is from sensors seeing different readings on the same shaft. overheating is from sticking t-stat.

I put a new thermostat in today and it seems to have fixed the problem. The temperature stays pegged right on the middle where it always used to sit.
I tested the old thermostat in boiling water and she was jammed shut.

I guess the engine computer takes over when the engine hits o/h. I'm guessing that it changes the timing and backs off the tranny so that it shifts early and very differently.

Thanks for your help!

Ken

any time glad to help.