How timely, and current! Op, I'm having the exact same problem as you. Car was perfect on an FP Green, went to a bigger turbo and the exact SAME thing you describe is happening to me. Get this: I got tuned on open source (wouldn't rev past 7250), now I'm tuning the accessport and the accessport doesn't let me rev past 6500! Crazy huh.
I've ruled out plugs, fuel pump, crank sensor. I'm not sure what else to try. The tune looks ok from what I can see, all tables reflect a 7500rpm redline. I'll keep watch on this and anything I find out I'll post.
I did log IDC at one time and noticed it did follow the issue, but I think something is causing that to fluctuate and not the IDC itself. Anyways I'll keep plugging away at a solution