I am having the same problem with my 02 grand prix (191,000). I've replaced the radiator tubes, both fans work when parked, flushed the radiator and put a whole new thing of 50/50 in it. Low coolant light is still on and hits 260*F (parked), 210*F (at red light). When I drive it goes down between 210* and 160*. This is so frustrating.