Thanks for the response. Do you know of the testing procedure for it? I'd rather diagnose the issue to be certain what needs to be done instead of throwing parts at it.

Thanks!

you cant test it without taking it out and by that point you might as well put a new one in.

Well, couldn't I look in the radiator to see if there is coolant movement? If there is movement in the radiator before the car warms up, wouldn't that indicate that the thermostat is stuck open and therefore not allowing the engine to warm up to proper operating temps? Or am I missing something here?

Thanks!

No need to diagnose anything. If the temp gage doesn't come up to 180 after 20 minutes, bleed the cooling sytem. If you find there is no air in the system, put a new thermostat in.

i think there would be movement in the rad regardless if the thermostat is open or closed because it goes other places

Looking for flow in the rad is a good way to make sure the water pump is working, but is not an indication of what the thermostat is doing.

There is no doubt in my mind you need a new thermostat.

I drove it for an hour and 20 minutes last night, and the temp never went over 190. Shouldn't this motor be running at 210 or something?

195 is rating for stock thermostat

How long did it take to get up to that temperature?

I drove for probably under 10 minutes to get to that temp, but then it never climbed. it stayed steadily below 195 that is for sure.
I guess I never really paid close attention to it in the summer, but I thought it was usually around the 200 mark. It wont even climb to that now.