Overheating woes yet again!!dlhdslf

[allenms240]

So, my girlfriend's car, 1993 Nissan 240sx Vert, is overheating. I have replaced the radiator cap, thermostat, water pump, and the radiator in search for the solution. None of this fixed it. So last night I raised the front as high as i could to burp out all the air out of the system, let it run for about 40 minutes of steady idle and saw some bubbles come out. She drove off to work today, and told me it was still overheating. When it overheats, it doesn't boil, or sound like anything out of the ordinary, but there is some coolant in the overflow. I'm lost here. I've done everything I know about the cooling system. I'm almost positive it's not a headgasket because there is no intermix, and the motor runs strong still. One day, I'll go rent a compression tester and test the motor for that, but like I said I highly doubt it. I'm lost, I don't know what to do and this car is frustrating, what do you guys think about this? What should I attempt at next?
I know this isn't the correct thread, but I've seen tons of technical stuff on this area and I know it gets more traffic. So here it is. Please help you gurus, I am stumped.

[asoomal]

When does it overheat? City or highway?

[allenms240]

Just daily driving it around. It's not the clutch fan, it doesn't overheat at idle, just when she's driving it to work or school. No highway.

[LoserCard]

One sure fire way to tell if it is the thermostat acting up or air is STILL in the system is to completely remove the thermostat and drive around a bit. If it no longer overheats then test to see if the thermostat can open and close by pressing on it. Then reinstall and bleed.

Also, does this thermostat have a air purge thing on it? It looks like a little piece of metal through a hole to let air through.

[JDM240SXcoupe]

It could be the fan clutch,thermostat switches, is the check engine light on?

[allenms240]

Ill test for a bad thermostat when I get time. Pull it out and drive around like that for a while.
There is no check engine light, I doubt it the fan clutch. There's a thermostat switch? Isn't the thermostat temperature regulated?