99TransAmWS6

Just flushed the fluid, and changed my thermo. Driving it seems to be right at about 210 Which i thought was alittle high. When idleing or siting at a light..it gets right on the line b4 the red. That dosent seem right to me. What could be the prob?

Injuneer

Did you buy the correct "reverse flow" t'stat? Did you install it facing in the correct direction? Did you follow the correct procedure for purging air from the system?

shoebox

Stock fans don't come on until 226º, so you dont' sound all that out of whack. It's normal for the engine to heat up when you stop, because there is no air flow across the radiator. That's just the way it works with modern engines that use thermostatically controlled electric fans.

JPSartre12

Are you sure that your fans are coming on? The fact that it runs at a reasonable temperature while you're moving suggests that it may be the problem. I've experienced that happening to me with three different cars. One had an intermittently working fan due to a loose sensor wire. A slick mechanic picked up that one after it was missed by others. One had a bad relay and the third had a broken wire.
A bad waterpump can cause the same temperature changes, but quicker. My son, LTLHOMER on the board, had a 1985 Porsche 944 that would overheat sitting still. We were able to drive it home as long as we kept moving and didn't hit any lights. We had to stop and pull into a parking lot at one point along a 10 mile trip to allow it to cool a bit. Damn foreign cars.