Slowly overheating 4.0... im lost

Ok, im stumped
My xj has been overheating randomly for quite a while. (Trail rig only currently)
Has a new thermostat, new water pump, flushed radiator and block thru the water pump hole.. tried to remove the block plug but it seems to be stripped.
I got alot of crud out of it, but not really an abnormal amount.
I can start it and it will warm up to operating temp (200-210) and stay there, normally for about 20-30 min, sometimes longer. Then it will slowly climb up to roughly 220 or so. Now sometimes it will start to run like shit and even die, ile try to crank it and it will act like its hot (crank slow and hard). Sometimes i can get it to start back up, other times not.
If i do then it will actually overheat, (start overflowing into the puke tank, jump to 260 or so) and ile have to let it cool.
There isnt any coolant in oil or vise-versa, no smoke or steam from tail pipe, runs like a scalded dog until it gets hot.
I had dual electric fans and i was wondering if they were'nt big enough so i put a new clutch fan back on that i had from another project, same thing happened.
Radiator is hot equally all over,
Lower hose isn't collapsing
Cooling system holds pressure as it should,
Has a new radiator cap,
Im stumped and about to look for a new motor. This one has been living on a band-aided cracked block since i got it (frozen by p.o., i fixed it with jb weld and been fine for 4 years).
Any ideas before i give up on it?

what year

99, sorry

And it will get hot with the thermostat removed as well

Sounds like you either have alot of air in the system or you have a cracked block, head, or blown head gasket.

I thought that too, but the cooling system holds pressure for a long time, others with a blown gasket ive worked with always seem to leak it somewhere.. i know there isnt air in it and it doesnt ever lose any coolant,
Ile prolly just end up pulling it, its really not worth tearing into anymore

Possibly your radiator fins or the A/C condenser which sits in front of the radiator is clogged with crap restricting air flow past it to the radiator. Would hurt to hose it all down real good if you haven't in a while.

I did that too, always do after a trip, flows freely, i can see right thru them. I just find it wierd that the only symptom i have is overheating. No leaks, smoke, coolant loss, runs smooth until it heats up... idk lol

My 2001 jeep is doing very similar it doesn't always get hot just sometimes. I'm thinking it may be the thermostat on mine since it never had issue until I replaced it. The water pump went out and thought oh maybe this is the problem. Still did after brand new water pump. No fluid in oil no pressure or fluid loss AC blows super cold air always and engine runs fine. But it will go over 210 sometimes.

What condition is the radiator itself in? I've had overheating of this sort with old radiators whose fins have begun to rot. Cooling depends a lot on the thermal bond between tubes and fins, and by the time you see fins blowing out, it's worse than you might think.

"Holds pressure a long time" - how long?

If your upper rad hose has pressure overnight...

... It's probably the head or head gadget.

Holds pressure As long as its warm, 30-40 minutes maybe, and the radiator was new 3 years ago