Thinking about it, I believe one thing that plagues earlier Buick turbos like this '80 is the knock retard system mentioned above. It's less accurate than later systems, and I've heard it's difficult to replace. Others know more about these finer points in the Before Black section mentioned above.
With the Buick turbo there's "early" and then there's "earlier early."
With the Buick turbo there's "early" and then there's "earlier early."