Depending on how serious you are about race prep check out White Racing and Marine in Warren (whiteracing.com) I'm not sure how much or if any general repair work they do, but they have a wealth of turbo buick knowledge especially in tuning. I went through them for alot of parts and machine work for my rebuild. Worth a shot to check with them, I'm sure they can at least point you in the direction of a competant repair shop if nothing else. I dealt with Dan, he has an email address on the website as well.
p.s. If you think it may be your MAF don't go to a GM dealer. I made that mistake and $300 later they replaced it. Autozone may be able to read the code for free Im not sure.
p.p.s. Where are you in Michigan anyway?