I’ve spent quite a bit of time trying to figure this out. And I thought I’d pass on the results of my testing today to save other people the trouble.
P0299 is pretty common on the forums and YouTube, but no one listed an easy test that I used to determine what was wrong in my case.

I checked for leaks, because that seems to happen a lot in these cars as they age and all linkages were tight. So I went underneath the car (because I had to replace the O2 sensor in bank 2 anyways and wow, that one was really painful to get to.). So while I was under the car, I disconnected the exhaust right after the front catalytic converter. There’s only two bolts, and they have some sort of a spring mechanism on them. I went for a test drive and the turbo schooled up for the first time in a long, long time. The car wasn’t loud in the way I expected it to be with all of the exhaust disconnected, but I assume it was the turbo waste air coming through. It was very windy sounding.

so I am ordering a rear catalytic converter from rock auto for about $250. I sincerely hope to see if you guys some time.