Code P0133 CEL Change manifold gasket?

This all started when I thought to change my PCV valve because my car seemed to be using oil. It did not seem to in the exhaust, but it was not leaking and yet somehow it was disappearing.

So, after I changed my PCV, I started getting a persistent CEL code p0133. Slow o2 sensor #1. My Bosch sensor only had 20k miles on it, but I changed it anyway just to check. It made no difference.

Since my car had 145k miles, I decided to change the throttle, manifold gasket and PCV vacuum hose. This caused me to disconnect the battery. But several drives later the CEL came back on. I checked for exhaust leaks. Nothing found. I checked the wiring, it all seemed normal.

At first my code reader had an o2 sensor in range but in red as if something was wrong with the sensor. Then after several days it turned green as if nothing was wrong.

Someone suggested I change to OEM o2 sensor. So, I bought Mopar and nothing good so far. From time to time the CEL turns off with the code still there in the code reader. And then there are times where the code disappears all together and then suddenly it comes back.

I should mention twice I bought high octane fuel, and the CEL turned off immediately. But as soon as I use 87, it comes back. Coincidence?

Any suggestions on how to deal with this? I am tempted to buy new fuel injectors; they are aftermarket with 50k miles. Also about how long do I have before my Cat goes bad?

Okay,

I changed the pcv valve to oem. Reset. 3 days later p0133 came back.
So I changed the coils (after market, 60k hard driving), and then the p0133 came back and p0420 came up as temporary.

Then I changed the (after) 02 sensor to oem and the codes all went away.

But, now I am paying attention to my CAT converter. And I think the o2 sensor went bad because of heat and the Cat is probably going bad as well. Temperatures on the CAT according tothe scan while driving often exceeds 1500 degrees F. I tried Cataclean twice. It didn't help.

So I think my oil (maybe) is ruining my CAT which ruined my o2 sensor. So I am going to try STP to see if it helps the leaking. Although, frankly, the exhaust doesn't seem oily or smoky. But The oil has to be going somewhere.

Thanks for the help. I am looking at a magnaflow CAT.