more ******* around yielded more information.
1. my obdii scanner usb connector broke and wasn't making contact so I couldn't check the MIL
2. after fixing #1, the MIL revealed itself to be a P1345 Cam Angle Sensor.
3. I started the car and let it idle for a while. After several minutes of normal idling, it started doing a weird "buh" and the idle would go briefly unsteady. It did this a few times (I was logging, nothing was obvious) and eventually crapped itself out.
4. I couldn't get it restarted, though it was behaving much more like it wasn't synching rather than just dead-dead.
5. Dug out one of my spare cam sensors (yeah, plural) and switched it in.
6. Started the car right up and the MIL was out--obviously it figured out there was a working cam sensor and corrected itself.
7. came inside to evaluate the original sensor:
You love my hack job, I know you do. Surprised it lasted as many years as it did.
The reason I never replaced it was because those god damn sensors are SO easy to break I figured it wasn't worth the effort.
So there you have it. zoom.