-you're in the wrong forum, but there are other considerations such as water pump impeller being worn to nothing, a plugged up radiator, faulty temperature sensor. I'm sure the Grand Cherokee forum can give you more specifics - we're all about the 4.oL here.
-you need to stop driving your vehicle overheating like that. Mobile office or not, if you crack the block, warp the head, or blow a head gasket you will become a static location with a serious repair ahead of you.
'00 XJ Sport, White - almost done for now...
'11 Town and Country - people mover :-(
'88 XJ Up Country, '01 XJ Sport, '08 KK Limited, '98 XJ Parts Donor, '07 XK Limited (the Stall-ander)