Running hot in 4 low

[beeline08]

I got my 2000 sierra out for some riding through the hunting lease for the first time this weekend.  Nothing real terrible just some slick spots and a few mud holes from a lot of rain the precious couple of days.  After riding around for probably 20 minutes or so in 4 low I noticed that it was running about 3/4 the way up the temp gauge.  I was at a gate so I put it in 2 hi and headed back to camp.  It immediately started to cool off and ran normal.  Normal is probably 200ish.  It hasn't done this since.  I checked and there was nothing restricting the air through the radiator.  Like i said it wasn't mud bogging just getting through.  It also didn't seem to have much power while in 4wd either hi or low.  In some of the slick stuff I would really have to punch it and after much hesitation it would go and still not really spin the tires.  It does have 35's on it but I was really surprised by this.  Is this normal?    

[txab]

Always check the fan clutch for proper operation. Plenty of videos on Youtube showing how. That's where to start