After filling the tank (or less), it would take several long cranking attempts to start unless I pressed the the throttle pedal while cranking. This happened every time I gassed up.

After a couple months of this, it finally lit the CEL, with an EVAP system, large leak.

The fix (after 3 days in the shop) was to replace the purge valve.

My guess is that the valve was stuck open, so when I filled the tank, the rich fuel vapor just passed through the charcoal canister and flowed into the (large) intake tract.
This resulted in a too rich condition, unless I let in more air by opening the throttle.

(The fuel filler neck is a tight fit around the standard pump nozzle, which probably helped force the vapor through the system, instead of outside.<ul><li><a href="http://webpages.charter.net/dwarner2/A3Start.wmv">Video</a></li></ul>