@Wagoncruzer I had a new OEM thermostat several years ago that had similar symptoms. Put the old one (which had only been in for a few years previously) back in and temps went back to normal. Last year when I did my t-belt and WP service, I put another new OEM thermostat in and had no issues.
Coolant flush and fill should be a priority. Closely inspect the radiator.
I’d also consider a transmission fluid drain as fill. Not a complete flush.
I agree with the above advice the other fluids need to be done but you can spread them out.
Have you tried cross-posting for assistance in the Mud Clubhouse that is nearest to you?
https://forum.ih8mud.com/categories/north-american-clubhouses-east-region.6/
Maybe try - FJ Northeasters – A Toyota Truck & SUV Community in the Northeast United States - https://fjnortheasters.org/ or...
I second the Michelin Defenders. I've ran them on my LX470 and as soon as it is time to I will get a set for our LX570
A very good comprehensive thread on them here on Mud.
https://forum.ih8mud.com/threads/so-i-think-the-michelin-defender-is-the-perfect-all-terrain-tire-for-most-of-us.1319040/