T-stat problems there are two in my galant!

Hi..I have a galant with 99 chassie, a 2001 hood, 3.0 v6 engine not sure of yr but Im guessing its a 2001 or so. The engine is strong an has power. (1) problem, it overheats while driving. I took out both t-stats, upper and lower hoses and still it gets hot. Itsnt it supposed to run cooler (constantly). Any ideas? Also the water inlet (or is it outlet) from therm housing to heater hose o-ring blew so I replaced it, three times, it still has a leak! I even put two rings and cant get it to completely stop leaking.