I have the '97 OEM radiator with 248K on it and if I were to let mine idle for 20 minutes, with or without the fan on, it would het to the 240 range and might even boil over. Yet cruising down the hywy my gauge reads 180f to 190f depending on outside temp and how fast I'm moving! As long as your temp. will return to the "normal" range within a couple of miles with a steady rpm of about 2k or more, you likely don't really have a radiator problem. If your fan will come on at about 212 degrees, it's doing it's job. It can not keep your engine from eventually reaching the over-heated range at idle. JMHO
the fan is not coming on at all, i replaced the thermo fan switch, and started to fell the radiator and down by the fan switch is alot cooler than the right side of the radiator