I think CO Saab nailed it.
I wish you would have said somethign earlier!!! I make all my mistakes so that other people can learn from them!
For about two months before SOC, I used my stock ECU with my 16T turbo and mods (DP, IC, full exhaust) and I was getting a boost cut midway in the yellow and fuel cut at 4,000 RPM. The car handled like a slug.
With the new ECU, it's a whole different ballgame.