Well, since I'm no expert, I am pretty good at guess-timating. So this is my educated guess...
After speaking with you guys, and getting input on this frustrating situation I was in, I followed a few steps and came up with the only thing I can possibly think might have happened.
Someone stated in checking for water pump failure, open the cap and let it run until it gets hot and the coolant starts to circulate. This will tell you that the pump is doing it's job.
After doing so, I decided to un-plug the Temp Control Sensor. Which I was also told would make the jeep turn on the fan. Since the relay I had kept the fan on all the time, I swapped it with one that wouldn't to see if it would still kick on.
Approximately 30 seconds after unplugging the temp sensor, the RPM's kicked up and the open radiator erupted coolant everywhere.
I figured that since the Temp control sensor tells the computer when to turn on the fans and do what it does to keep the engine running cool. That it was apparently failing, not at start up, but during road use, causing the radiators to build up pressure they couldn't hold.
I bought the new cap with release valve which seemed to help, but not sure if there is anything happening there. It still got hot, but I shut it down before I ended up buying a FIFTH radiator. However, the relay for the fan had a better response to the new Temp Control Sensor than it did for the old one. I never bought a new fan relay, I re-used one of the 8 I had and when turning on the AC it came right on, and turned off when I shut the Jeep off. The boiling over of the overflow reservoir hasn't happened at all and the loss of coolant has subsided, since the temp sensor was replaced.
As odd as it may sound, and trust me, it's ALL Greek to me, this is the only guess I can come up with as to how I managed to fix it. With ideas from you guys and a really good guess on my part.
A $30 Sensor, if it weren't for warranties, might have cost me over $500 in radiators and give or take a head gasket or new replacement engine! Amazing! ...not to mention the mental anguish that went along with it all!