The car is a 96 thunderbird lx...the radiator is fine-I'm pretty sure I have a leak somewhere between the overflow tank and where I put the fluid in at, but that's a simple fix--I constantly check my fluids before I go anywhere just to make sure I'm not low or whatever.

I know it is actually overheating because yesterday on my way to school I pulled over and some creepy trucker guy stopped to help me and he took the metal cap off of the radiator and it was very. very. hot (which, I'm pretty sure you're not supposed to take the cap off while the car is hot, right?)

So, if the thermostat is off, that could cause the overheating?