I've read a lot of posts about people's tegs overheating while idle, but none of them seem to have my problem, or maybe they haven't tried to do this.

95 LS auto.

Situation:

after 10 minutes of driving i was going through a drive thru and while i was idling the temp gauge almost went all the way to H.

As soon as i moved, im talking from one window to the next it dropped down to below 1/2 (regular). When i stopped it started going up again.

I thought maybe it was because i was in such a confined space (drive thru lane)

however, i stopped at a redlight and it started doing it again. It only does this when the engine is idle. if i stick it in neutral and revv the engine, the gauge drops. if i keep it in drive it goes right back up to H.

as soon as i hit the gas pedal it goes back to normal.

what could it be?

thanks in advance