Hello all

background:
'01 grand prix GT
3.8L engine
~95K miles

My check engine light has been coming on and the code was for a coolant temperature sensor, so i replaced that, wiped the computer so the check engine light wouldn't come back on, but it did.

I'm thinking maybe i need to to flush the coolant/radiator and replace the fluids because i saw some brown gunk around the radiator cap. Or maybe replace the thermostat.

The temp on my engine gets up to 210 pretty quickly and I've been running the vents to try to keep it cool. Then today, the check engine light went off and the temp reached about ~235

What would you guy do in my shoes?
Thanks