It's probably your lights. My truck started having highway speed over heating after I put my winch on. ONLY above 65 mph. Must be disrupting airflow at that point.
If it doesn't over heat at low speeds, I think your losing airflow across your rad at high speed.
Only other thing I can think of is your lower radiator hose sucking shut at high rpm's. Never seen this on a Toyota but, I have seen it on other equipment. Usually on hoses that are supposed to have a spring inside to keep them from collapsing but, are missing the spring. Also seen it on oil soaked hoses that get real soft. You said new hoses though.
Did the problem start after you put the bumper and lights on?
Honestly I dont really know. I have only owned it for about a year. I bought it from a guy in cali and drove it home 4 hours to vegas and it ran at 180 the whole way home. Then it spent the next several months of it's life in the garage and driveway getting prepped for paint and put back together. When I bought it and drove it home it had an arb bumper with the same lights on it. The lights sat a lot closer to the grill with the arb and now they stick way out there and there a lot closer together. You might be on to something I will take the bumper off this weekend and test run it.
The day I got it home.
Almost ready for paint.
Fresh out of the booth.
