I put a thousand difficult miles on my XJ in the past week during another trip to the Sierras. What I discovered is that some of my low speed over-heat issues persist but my high-speed and idle issues are resolved with the new fan clutch and radiator clean/flush. While driving through the desert (ambient 97º) I was in the 220º range, going up hills the temp would rise to 235º but never go past that last white hash mark and into the red. At idle it would never go above 220º even if it idled for an hour. Going up steep trails still pushes the needle into the red and I had to stop a couple times to let it cool off. On the other hand, low speed, flat trails in the desert with the AC on never went over 220 so it has to be the slow speed climbing that's causing issues. Watch the Scenery forum for trip notes and pictures, I'll get them up sometime this weekend.