I have a 93 3.0 3sve, (well there's your problem) lol, Anyway it runs hot and has overheated once before. the only time it displays these symptoms is at highway speeds 60-70 mph. I've had the radiator out and itlooks to be in real good shape, I'm thinking it's not the original. It has ajn aftermarket electric fan that also seems fine. It has 33's (4wd) and a cap so it's not the most aerodynamic ride. Plenty of OEM Toyota grade rust has also lightened it up a bit. Can someone cool my ride
Make sure that electric fan is not impeding air flow at higher speeds.
I just had the same symptoms and it turned out to be a cover installed on the Taurus fan put in place to help the fan pull more air at idle. It was not allowing enough air to flow at speed. Removed the cover, which meant that fan was no longer fully sealed against the radiator, and the truck's temp gauge is stable as can be.
Frank