Your stalling, no start issue, The Crank Position Sensor CPS is the weak link in the ignition system and often a culprit. $60. I carry an extra one under the back seat.
I've also had the throttle position sensor go out on me before.
Oh yeah, vacuum is always a sneaky culprit as well. Check for leaks.
If you can find someone with a OBD-1 scanner that will help a whole lot.
Here is a nice site on engine sensors
http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

I'm in San Luis Obispo, so a good 4 hours away from Long Beach.

Actually, that fan shroud has been cracked at the top, but I didn't notice it causing any problems. The fan had still been spinning. But, now that I think about it, I don't think it was spinning when I had the Jeep idling today. But could that little fan make such a huge a difference that it overheats in 5-10 minutes?

If the radiator is the culprit, I'd definitely invest in upgrading it, as you're the second person to recommend it... I suppose I just have to figure out if my cylinder head/head gasket is hosed or not first.

 

Yes, the fan shroud and mechanical fan are HUGE!!!
I once replaced it with an electric fan because I read a post that said it was the coolest. The fan burnt out and I couldn't make it up to Sequoia, I was over heating like it was the coolest. Not so cool. I had to come back down the mountain.

Check the operation of the mechanical fan. If it is original (OG), and it probably is replace the fan cluth with a heavy duty one.
The fan shroud channels the air and makes a wind tunnel, you HAVE TO HAVE THIS!!!

The radiator is probably old and would not be surprised if it has reduced flow. If you call Jeep Solutions ask them how you can mail order the 3 row metal radiator that uses the 89 fan switch. I converted mine to the new style radiaor (radiator cap, Open System) with the new thermostat housing and new style fan switch. I had to splice in the new style smaller switch in the thermostat housing. I later found out it didn't have to be that hard.

BTW, Jeep Solutions costs an arm and a leg but they have been in business for 30 years customizing Jeeps and they do it right. You get what you pay for.

I've had my 89 for 14 years. I've figured out a lot of headaches over those years. I wouldn't trade it unless Jeep came out with a re-issue of the Cherokee after consulting with Jeep 4x4 enthiiasts and integrated a real frame and kept the I-6 engine.

I blew a cylinder towing a trailer coming back from Mexicali in 2003. I made it back to LA towing at 45mph. Unstopable even with a blown engine.

 

That fan should always be spinning, correct? If so, that must be a part of my problem. It doesn't turn on/off based on temperature, does it (in which case there could be another cause)? Suppose it wouldn't hurt to replace the shroud, too.

I just don't want to throw parts/money at it if the cylinder head or head gasket are shot... as another poster suggested, that the oil level is showing above the FULL level on the dipstick might imply that I've got water/coolant mixing in there (though the oil color looks normal)...

I guess flushing the radiator and changing the oil would be the first step...? If that can get the Jeep running normally again, I could then look towards upgrading the radiator.

 

When at idle the fan definitely should be turning. With the engine off the fan should not spin freely. It should turn by hand with resistance.
When operating, the clutch will allow the fan to float at highway speed since there is a lot of air coming through the grill. It is a tight fit to replace the fan clutch. I removed all the hardware above and around the radiator so I could manipulate the radiator to increase access.

 

My bet would be head gasket. oil level to high and to much pressure in the cooling system are sign of a bad head gasket, buy a compression tool, about 40 bucks and perform a leak down test. If it does not hold pressure the gasket could be bad or it could be a cracked head.
do this before you waste time and money upgrading your cooling system.

 

I have had the same problem lately my 90 limited is 4.0 automatic and has the closed radiator on it also, i have never experienced it stalling yet but it does run hot and it blows the antifreeze right out of the bottle and even the hoses on the radiator, i plan to change out the radiator and shange to an open cooling system, but just to be safe i am also gonna do a head job and check all major gaskets, if anyone has any other sugestions please let me know

 

I was mistaken, the fans are all spinning. But whereas the fan shroud once just had a hairline crack, now half of it is missing, so I imagine that is a contributing factor. Whether that should lead to the water/coolant bubbling/boiling after idling for only 5 minutes, however, is another question...

I still have to empty out the oil and figure out if there is water/coolant mixed in... guess that is the most important test.

 

you can have the cooling system pressure checked at any automotive repair shop that would be step one.