94LexES

First question is: Why does my temp gauge go down when I'm on the highway then it comes back up when I'm not on the highway?

Second: My car idles at 1K once it's warmed up, is that normal?

DJPsystems

Thermostat may be stuck open.

94LexES

great... lol I thought it would be the coolant temp sensor?

hypervish

I agree, sounds like the thermostat is stuck open a bit. When you say the temperature goes back up when you are not on the highway, you mean it goes to the middle correct, it doesn't overheat?

1,000 rpm is too much if it fully warmed up, however i suggest waiting till you have replaced the thermostat to tackle that issue. The ECU may be trying to warm the engine up because of the stuck open thermostat.

94LexES

It doesn't even go to the middle at all, it touches barely above the second to last tic even after long trips. There's no overheating issues at all.