If the fans aren't blowing hot air, it tells me the system has air in it. Could it be a coincidence that the new radiator wasn't bled properly and now it's overheating? Unlikely, but possible....though it wouldn't blow hot from the get go.......
What does the underside of the oil cap look like? On a 99, the headgasket failures would typically be an external leak, so there might not be any milky residue under the cap....but there would be wetness on the block/heads near the back corners.
When the radiator was changed, was there any mention of excess coolant conditioner or stop leak? That crap is brown....and can gum up the system if it's not used correctly. It's possible that the radiator was plugged, simply replaced and now more crap has caused another blockage.
Can you feel the radiator in different spots? Feel for very hot on one side and any cool(er) spots.... that's a sure sign of circulation trouble, particularly in the thermostat housing area, where the junk likes to collect.
Try some of these things and let us know how it comes out.