Engine Overheating
 

I have a 1995 Grand Prix piece of $%!t. I am very tired of fighting this problem The problem I have is the motor overheats at start up. its worst when its below 32 degrees. Acts like the thermostat isn't opening. I have replaced the thermostat twice, the water pump once, the radiator was fixed for its leak, the radiator cap has been replaced, flushed the system, it has new 50/50 coolent, and the belt is OK. I also made sure to vent out all airpockets from the system by to 2 air bleeds located at the thermo housing and by the water pump. Can anyone tell me whats wrong before I trade this so called automoble off for a Honda Accord?