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You say you have been through the cooling system but define that a little better for us.
Is the radiator brand new, recored or just as it came on the car?
What is the thermostat opening temperature?
What mix of water/anti-freeze are you running?
What is the engine timing set at?
What condition are the radiator hoses?
Details will help.
Speaking personally; I have a 77 280Z stock with the stock radiator and a 16" Perma-cool fan. 180 degree thermostat and a 50/50 mix of water/anti-freeze. My car has factory AC and the electric fan NEVER runs (I live in Alabama so it is hot and humid) unless I am sitting still in summer weather. If the car is moving it just doesn't get hot at all. Some cars do have a hot nature, though.
Good luck.
Craig