Fixing over heating
 

I'm new here, but I wanted to get some ideas on what I need to do to fix my 92 4runner 3vze from over heating on long road trips in the summer. I drive from texas to south Carolina often and in the summer the engine suffers going through these hot states. The temp on my dash shows the engine is at proper temp but when I slow down from highway speeds the engine goes to red. Even if it's not at red the engine is so hot it severely burned my arm when I tried checking my oil. I saw some people saying that a cooler thermostat would fix that. Is that true, and what else could I do to make it run cooler?

It sounds like your fan clutch may not be engaging. When the engine begins to heat up due to lack of air flow in slower driving, the clutch should engage and spin your fan at engine speed to pull more air through the radiator. Also make sure the fan shroud isn't missing.
A cooler thermostat will still run 175+ deg, that's not really a solution for overheating. Usually it's caused by restricted coolant flow or lack of air flow, or low coolant level.

Like Moto says ^^, BUT in order to save you and us time, why not tell us what you have already done?
Have you done the standard preventive maintenance? See user's manual.