I have 1990 Camaro RS it keeps running hot I have a new thermostat on it and the fan is working.?

yeah, make sure the water pump is moving the coolant..

also, the radiator may be clogged...

Is the coolant and the oil relatively new? Low or very old oil can cause overheating. A bad sensor of some kind might also cause overheating but if that was the case you'd probably be throwing some kind of code (i.e. "check engine"). Oh and is your radiator cap on all the way?

It might be the water pump,also be sure your resorv is full,plus if you leave your radiator cap loose all presure will escape esier,just put the cap on push down turn but only till it's locked not tight though.

Is the temperature fine when it idles, or does it only overheat when you are driving? If it does the latter, be sure and make sure your air dam is still in place. F-bodies will overheat without the air dam if they are in motion.