The only times i personally have had problems with creeping temps like that when idling, crawling, or or whatnot, was either cause by a bad clutch not engaging, or the radiator was old, and several if not most of the rows were rusted shut and not allowing for full flow.
I DO still have this problem now, even with the brand new heavy duty fan clutch, and 4 row radiator, but i am certain it is because i have yet to find the correct fan shroud for it.......running without it at the moment.
Only heats up on the trails though, hasn't done it on the street driving in traffic yet.