Could be a few things.... maybe an air bubble in the system, bad temp sender, water pump, check the electric fans and make sure they are blowing the correct way(if mounted in front of the radiator they should blow through toward the engine, if mounted on the back of radiator they should suck air through.....
you might have to do a little more research on your car to give us some more information.
StingrayJim
NCM Lifetime Member #1936
Stingray's '76���������������������������� StingrayJr's '78���������������������������Lil Red '94
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DanT