'99 Getting high water temps

[Crash1181]

I just started noticing my '99 SE is running a little hot. I'm not sure I've ever really heard the radiator fan come on until the other day. Now I notice it coming on quite often, and earlier today I watched my temp gauge really closely, and it was moving around erratically. I've never seen that thing move past midway ever. Now all of the sudden it's climbing up past halfway. I have 150,000 currently, and as far as I know the thing is bone stock. Also, I examined the radiator and I'd say about 1/3 of the fins are useless due to being crushed. Lastly, when the electric fan comes on it's kinda loud, so I took a look and either it comes with crappy bearings or mine are worn out because it wobbles around a bit. Is this normal? Also, what is your hunch as to what may cause this? I'll probably pick up a thermostat first since they are cheap. Is my sending unit going bad which is cause the fan to come on because it thinks it's getting hot?

Edit: one other question.. do you guys like to keep with the standard 192 degree thermostat or go for the cooler 180 degree ones?

[AzTumbleweed]

I replaced my radiator at around 200,000 miles because it was clogged up. I found that the top portion of the radiator would be really hot and the bottom part was cool to the touch. (That's where the clog was.)

With the temperature sensor feeding info to the computer I no longer use a thermostat that's anything but stock. Low coolant temp could make the engine run rich.