Another MJ Running Rich

[SoCalManche]

1986 Jeep Comanche 2.5L seems to be running rich. I've scoured CC on other running rich scenarios, and it seems like the culprit 9/10 times is the 02 sensor. I have a bit of a different scenario for you folks. When she starts up, she evens out on her idle and sounds good; sounds really good actually. However, I have what I feel may be an excessive amount of water with some discoloration. Here's a quick video of said tail pipe action: https://drive.google.com/file/d/1BrjBtLbsyfzmVeayyzdZG3ll8TpFgoj1/view?usp=sharing

 

You'll hear some rattle, and that's the cat; she just up and recently started rattling like crazy, and my muffler guy said the core is shot (not the shield around it), so one is coming Friday to get thrown in. Spark plugs are also under a month old, and are already fouling. My question is whether or not that is a normal looking symptom for a cat being shot, or if that is excessive? Definitely have rich fumes coming out, however I've tested every sensor on the TBI, and everything seems to ohm out how it is supposed to. The other thing I need to mention though is that she doesn't seem to get fully up to temp, so I've read on here to just get a thermostat from a dealership and be done with it, and that should alleviate the issue to a degree as well. 

 

Just looking for some peace of mind with this rich running condition because I've been racking my head around the sensors seemingly being in functional order. Does having a bad cat AND possibly a bad thermostat cause this kind of exhaust as seen in the video above? Thanks guys.

 

[Pete M]

is the video from when you first fired it up?  or after it's hit operating temp?

 

If you have no idea when the o2 sensor was last changed, it might not be a horrible thing to replace it just because.  

[SoCalManche]

I replaced the 02 sensor within the two weeks ago with a Bosch one before the cat started rattling. Ohm'd out both the previous 02 sensor and the new one, and the old one actually has less resistance. That video is at operational temp, or at least what it can get up to, which looks like it reads out at 175-ish degrees maybe? I'm swapping a new Motorad thermostat in today as we speak to see what change may occur.