Unintended acceleration

[C. David Nelson]

Well, never having experienced this myself, I had just assumed (as I've
read here and elsewhere over the years) that this was an imaginary
phenomenon created by someone who couldn't tell the brake from the
accelerator, and compounded by 60 Minutes.
This morning on the way to work, however, I was plodding along in my
wife's '96 A6Q at about 55 mph when it suddenly felt as if I'd
accidentally hit the resume button on the cruise control: it continued
to accelerate until I was able (barely) to bring it to a halt with the
brake and shut it off.
I was hoping it would heal itself after I shut off the ignition, but
when I turned it back on it idled extremely high in park.
Any BTDT suggestions for me to pass along to a local mechanic or
(shudder) the nearest dealer an hour and a half away in Evansville,
Indiana?

Dave Nelson
'90 V8Q, ca. 180k miles (now daughter's)
'96 A6Q, ca. 122k miles (wife's)
'98 Contour SVT (also in the shop)
'90 Corrado (I guess now my daily driver)