Re: 00 jeep grand cherokee?
I'd start by trying a radiator flush, it may need flushed out to get rid of any debris that may be causing your problem. And also check for any leaks, bad hoses, etc. I had the same issue with a prior vehicle and did the same things you've tried, flushing the radiator, new thermostat, new radiator cap, and new hoses solved my problem.
2001 Silverstone Metallic WJ Limited
2005 Black Chevy Tahoe Z71