I was wondering if anyone knows what could be going on with my rx7 it's a 1990 fc. When I cold start it in the morning it just over heats I don't know if I should let it warm up before I drive it or if something else is the issue but when I drive it at night or during the day it does just fine. Does anyone know what could be going on

 

You should always let a rotary warm up before driving it. Start by checking to see if theres any coolant in it. If there is, try bleeding the system. If that doesn't work, my best guess would be it's time for a new water pump.

 

It shouldn't over heat regardless of whether you let it warm up or not. Though probably not a bad idea to let it warm up a minute you don't need to let it get to normal operating temperature before driving. Along with the already suggested checking the coolant. You may want to start by changing the thermostat. They are not expensive nor difficult to change.
Does it only over heat when sitting still during warm up? what about any other time you are stationary and not moving? Odd it would only do it when cold. If the water pump is failing it should be leaking from the weep hole. Check for coolant around the water pump. Make sure it's not leaking anywhere else.