Previous owners could not figure out the issue. The car's engine would rev "bounce" at idle like it had a big cam, but it didn't go away when driving, making driving not very fun. So I got the Scirocco for dirt cheap.

I realized on day that if you opened and closed the hood a couple times, the issue would fix it self, and it was very repeatable.

I realized the computer is mounted next to the hood hinge!

I got lucky and just blindly resoldering all the joints in the computer fixed it.

We later swapped that 400k mile motor setup to a modern turbo motor with a sequential gearbox, and it's a rally car now. :)

(not super important to story but the "ECU" from 1982 was a bit more modern, Jetronic as it was called was "only" roughly the size of a few old TI-82s).