Frustrated

[prpldwg0507]

I have a 1985 Firebird that is overheating. I replaced the thermostat and still overheats. I take out the thermostat and it doesn't overheat. Both hoses are hot water is flowing I'm at a loss can someone give me ideas of what it could be. Thank You

 

[R_T_71]

I have the same car, wich i am assuming u have the original TPI engine in it.
There is a electric fan on mine, so im guessing there is one on yours, there is a temp control switch for the fan that could be bad, or the fan itsself.
Have you ran the codes yet and see what it says?
On another note, depending on where you live, running it w/o a thermostat it will over heat on long hauls.I live in the mountains, so i know mine would overheat.