Do yourself a favor, take a break from the car. Be it a week or a couple months. Then before touching it, search for someone in your area that is a master GM mechanic (not a trainee or a tech) but a true certified GM master mechanic. I'd also search for a certified master tuner, though I don't know if such an occupation exists. There has
to be someone in your area that is an expert in turbos & tunes, find them!
The point I'm trying to make is that it is never a good idea to make a decision about something when you are frustrated. Like I said, take a break from the car, enjoy life, and then tackle it at a later date. Meanwhile seek the help of an expert one last time. Hang in there.