after a lot of tinkering around, nothing worked, so I just ended up replacing the coolant sensor. Unfortunately, at least for 2000 GTs, the sensor comes with a new tank which cost about $97 plus new coolant. But I guess it was worth it cuz now the light is finally off!
2000 GT Covertible (AOD)
19" Konig Appeals w/ Dunlop SP9000,
Eibach Pro Kit, Baer 13" Brakes,
Powder-coated red calipers,
Flowmaster 40s, HID upgrade, Billet Grill, Red interior trim, Pioneer AVIC-N3, JL 10W7 in custom box, JL 500/1