Yesterday I exited the highway and noticed my engine temps rising from the usual 195 to about 215 degrees. When I come to a stop, it returns to 195 and stays there.

As I accelerate up to speed it continues to stay normal at 195, but as I'm cruising (30mph), it rises up to 210-215, then goes back to 195. It repeats this process over and over while at cruising speeds.

I had a similar issue a couple months ago, only it would rise to 220 and stay there while cruising, then drop back to 195 at a stop. I replaced the thermostat and that fixed it instantly.

What do you think the problem is now?

Thank you