Engine Cooling problem
2004 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic 120000 miles
I have replaced the radiator and the thermostat about 1 year ago. Everything has been running fine up until about 2 weeks ago. It's been doing the same thing. Sometime when I drive on the highway shortly after start up, the temp gage will be down by the first line(running rreally cool). But, if I just leave the car running while in park, it will overheat fairly quickly.
Now, on my way to work this morning(while on the highway) the heat gage was in the red.