Idles fine, but stalls/dies at 2000+ rpm - long post, please help

[ATWork8803]

It sounds like you're doing the compression test with the engine running - is that correct?

That is correct. How else do you get compression?

Edit: I just looked it up. Gotta disconnect the coil so it only cranks. Hmm. I was listening to the guy who let me borrow his compression gauge. So does that makes my results invalid? Or worse, could I have caused any damage??

Edit 2: Did a little more looking and it sounds like I just did a "running compression test," though much less thoroughly than a pro. One thing I read is that the running compression should actually be lower than static and at 200 psi, I'm running pretty high already. One source suggests clogged cat converter, which, along with my rattling exhaust could be something worth checking.