Got a 98 GT with the 32V cobra motor in it. Last week the car was getting a lil warm so I changed out the coolant and thermostat. Turn the car on a let it sit to burp the air out the system. It seemed to never fill with water as I was told it would eventually do, so I replaced the radiator. Now you can see a steady stream of water going across the bypass tube and it fills up the resivour OK. Get on the highway and 20 minutes later the car gets EXTREMMLY hot. Shut it down and let it cool then opened the bypass tube and its full of water. The car overheats on the highway with the ac and without it. Its getting way hotter than it was last week. Local shops are dumbfounded and have no clue. They say the water pumps good, the radiator is good, it holds pressure, and theres no CO2 in the coolant (bad head gasket sign). What else could it be. I got a new water pump and am going to tear down the engine to look for blockage of the water passages, but before I do all this I wanted to see if theres anything else that I might want to look at??? PLEASE HELP!!!!!!!