Finally got it after spending way too much time on the problem.

It turned out to be the wire that runs to the under-hood light. It had chafed through at the clip that holds it and the rubber seal to the cowl. I had pulled the wire previously, but not out of the clip - it looked fine. It wasn't until I actually pulled the wire out of the clip that I finally saw it. Very obvious at that point.

In my defense though, I was led down a stray path with the wiring diagram that was in my Haynes manual. The manual didn't show the wire that goes to the radio for the preset memory. That got me kind of mixed up.

Oh well, the job is done! New headliner and sunroof panel are in and it looks terrific. And everything works. Thanks for the help.

(Tried posting a photo in this reply but I keep getting the "404 File not found" error. A photo of the offending wire is in the technical gallery.)