Have brought the temp down a few degrees on my 88 Cherokee. It now idles around 210 degrees. I was able to come up the mountain today and the guage regisered just below the last white line and the engine did not boil over. Seemed to stay a couple degrees cooler if the rpm was kept above 2500. Would still like to drop the temp a couple more degrees. I notice that once it gets hot it takes a long time to cool down at all. Is this a mixture problem? I'm now at about a 50/50 coolant mix.

Ah, the saga continues....

Actually it sounds pretty normal now. I also have an '88. It idles around 200-210. On a warm day, the electric fan kicks in above 210 and starts to cool it off a bit. It will run cooler at higher RPMs since you're circulating more coolant. Mine takes a while to heat up and then seems to hold the heat as well.

If you want it to run cooler, you could hook a manual switch to the electric fan so you can turn it on whenever you want. This would be the easiest and cheapest way to do it.

The electric fan comes on between 200 and 210 now so it's already on when it's idling at around 210.