Thanks for the reply. The cat was gutted before I got the truck, it looks like it is still there only is completely hollow. I have no idea how that is even possible because running a pipe through there just makes a pipe sized hole right? I discovered this after changing the down pipe because the flexi part of it had a leak.
As for the steel wool comment, the steel wool is to be pushed into the spark plug anti-fouler and the o2 sensor screwed into that, the anti foler screwed into the pipe. I read this on some hyper miler websites.. Because several different sites suggested it, I assumed it was a known thing.
Can the downstream o2 sensor keep it from running in closed loop?
I recently replaced the battery and the check engine light came on about forty miles later..