Just replacing the stock fan with a new one might help. The stock fan could be wearing out or your water pump could be wearing out.

I've never let mine idle that long, so I can't say if 235 is normal for extended periods of idle. What is the temp while cruising? Mine is normally around 180 if I'm going 55+mph.

 

Around 185 cruising on a cool day, around 190-200 cruising on a hot day. If I cruise around town slow on a hot day it will easily get to 220