I have a '00 ex v10 with 119k miles on 35" tires. was towing a 5k travel trailer in 100 degree heat. My oil temp light and service engine soon light came on I pulled over and shut the truck off. waited about 2 minutes and started truck again. Oil temp light was off, sevice engine soon light was still on. Drove about 5 miles more down road and Oil temp light came on and temp gauge shot straight up and truck lost power. I pulled over and put the hood up. Radiator bottle was not boiling, i checked the oil level and it was right at the low mark on the cross hatches. I got back in the truck and started it and kicked the heater on high and the temp went right back to operating temp which is about 1/3rd of the way up the normal operating range. This is also where the temp had run for the previous 150 miles towing the trailer thru the ozark mtns. I pulled off at the next exit and added a quart of oil, unhooked the battery to shut off the service engine soon light and let the truck set for about 20 min. I then drove another 45 miles at 65mph with the same trailer, outside temp reading 99 both a/c's running on high and the temp gauge stayed right were it always sits. This is the first time i towed my tt on a hot day but i pulled it on the same trip 2 weeks ago when it was about 82 and the temp gauge never moved. I was thinking the temp senor may be going out. Any advice would be greatly appreciated.
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Oil temp light? Not aware that existed.

Anyway, it does sound more like a temp sensor, damaged/ loose wire, or sticky thermostat issue. I would recommend getting a hand held IR (infrared) thermometer. These are very handy to diagnose as you can shoot the engine, radiator, or whatever you want to see what is hot and what is not. It can really help you zone in on the root cause. Also handy to check brakes! If one is notably warmer or cooler than the others, you have a problem developing Takes about 2 minutes to walk around and check all 8.
Flipping on the heater is a great idea to help cool down the coolant circulating in the engine.

I have towed heavy in 110+ degrees and temps stayed in control. The radiator in these things is huge. I love it!

As an aside, I choose to replace plastic tanked radiators at 10 years. I have had a few fail at about 12 to 15 years old. If you like the truck and plan to keep using it, I would recommend changing the radiator, hoses, thermostat, and belt as PM. And flush the heck out of the block when hoses are off. Changing water temp sensor at same time wouldn't hurt and is cheap.