Now you jinxed it!
Could be, because another part bit the dust. I was driving around, testing the AC, when the get-up-and-go got up and went. I turned off the AC, and still no power. And it was worse the higher the RPM got. Felt like a clogged cat.
I originally wasn't sure whether the thing at the cat position was a cat or just a muffler, but since I had felt it get hotter than the rest of the exhaust system after a little running, that told me that it was a cat. So I cut it out. Inside was some very fine honeycomb structure, and the structure on the intake side was broken up. Fortunately, the structure on the output side was still intact, so no junk got blown into the muffler.
So I got an appropriately sized "test pipe" at the parts store and put it in. The get-up-and-go is restored, and the exhaust sounds better now.