Jump the fan switch and test drive with fans running all the time, if it still overheats it's not a fan problem.

the fans come on because the coolant leaving the radiator is hot. This implies that there is coolant circulating from the engine through the radiator, which requires the following:
system full- if dry there will be no circulation
thermostat open -- if stuck closed again no circulation.
radiator not clogged-- that can be ruled out now since you have a new one.

 

Could you elaborate on that one a little bit? Are you asking if the system has enough coolant?

 

If there is a pocket of air, the coolant doesn't circulate well because the water pump can't move air. It really sounds to me like there's a slow leak in the head gasket. Get the system as full as you can then let the engine cool off fully. Next start the engine with the radiator cap off and rev it up. If you see bubbles steadily coming out, the head gasket is leaking. A severe case will have coolant surging out of the radiator.

 

Yeah that's what I've been thinking, just been hoping for someone to tell me otherwise. It's really strange, it overheats when I'm idling, but as soon as I hit higher speeds, the temp gauge goes back down.