flash_xx

Change the water pump. Get the Edelbrock one.

Tivo304

Water pump is fine, no leaking, turns smoothly, even checked whether the impeller was cycling coolant well enough by turning the motor for a second with the block's coolant bleeder valve unscrewed (yes, coolant spat out like a pressurized fire hose).

Just posting for anyone who might run into similar issues: Turned out to be bad O2 sensors with no codes thrown (somehow). Car runs, idles and accelerates like new with no overheating. Head temps stay around 200 even driving "spiritedly" with the new Mishi rad and FRPP fan. Still glad I replaced the radiator/fan with upgrades, turns out the GT uses the same wimpy stuff as the V6. Sad.

flash_xx

Glad you found it. I also replaced my 02 sensors even though they weren't throwing any codes and the car performed much better after.