-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.
I'm back on my court mandated Rx. Other than the drool shorting out my keyboard, I'm here to help!