Fixed!

Damn spiders!
I disassembled the distributor to check out the cam and crank position sensors within. What I discovered was a nice assembly of dust and those tightly woven spider webs covering some of the guts of the distributor.
I cleaned it all out and re-assembled it, and POOF! it times right up and runs perfectly. I guess the optics of the sensors were being partially blocked by the junk, keeping it from working correctly.
I'm not even sure how a spider got in there. It all seems pretty closed up and well sealed.
Anyway, many thanks to all, your advice led me to where the problem was.