I did find this place in Champaign that seems to do Porsche work. They advertise that they do a PPI on their "services" page but I don't know how qualified they are. I guess it would be better than nothing, as I'm not going to be able to get the owner to drive almost 200 miles to Chicago and the surrounding neighborhoods to a Porsche mechanic I have seen recommended for a PPI.
Rick's Automotive Service Inc. - Home