So, now my airplane is speeding up in the outside portion of the horizontal eights -- but not the outside rounds, or the outside parts of the vertical or overhead eights, or the clover. And it's going screaming lean, too -- it's not just speeding up a subtle little bit.
I did notice after my last flight yesterday that the engine was loose, so I'm willing to believe that's it, but I'd like to show up at the field with other possible things to look into if it's still doing it now that the engine is tight.