So it’s about 8 degrees where I’m at. My car was just fine a day ago but now when it’s idling, the temp decrease. When I drive it, it goes up to 198. It doesn’t overheat but soon as I stop driving, it starting going down. Anyone know what cool be the prob

So it’s about 8 degrees where I’m at. My car was just fine a day ago but now when it’s idling, the temp decrease. When I drive it, it goes up to 198. It doesn’t overheat but soon as I stop driving, it starting going down. Anyone know what cool be the prob