If it is not overheating and fan cutting in and out then it is just the guage.
Mine, 2wd sapph has a mind of it's own too, and regualarly hits the red and beyond before fan cuts in, sits for hours in traffic though, next day it could be on bottom of scale before fan!
I measured my temps and they were nothing like the guage was suggesting, best thing I ever did was to take off the sheild between rad/intercooler from front air flow!!
tabetha