I got ford to flush my radiator a couple days ago. I went to ford because they use that machine to clean it out. But driving last night my temp gauge started to move towards the red. It would stop about a 1/4in before it hit the red and go back to normal. I was on the highway going 70-75. It would do it when idling also. Then for 20 min when driving home I didn’t do it once. The fans do turn on. Think it’s the thermostat sticking? If it was the WP wouldn’t it just overheat all the way into the red? Oh and my heater does work.