The problem was old and brittle wires. All 3 wires that connect to the plug that plugs into the distributor had cracked insulation where the wires entered the rubber boot. The middle wire had corroded inside the insulation. Cracks were not visually apparent, but when I removed the plug to check voltage the wire broke right off.
I slit the rubber boot up the side and cut/soldered/shrinktubed the wires, then resealed the boot with Seal-All. Car runs fine.
(For previous threads, google "scirocco craps" w/quotes.)
nf