torque management issues?

[dian]

i am tuning a 99 c5 with a centri blower. using os 02020003/cos3. all was going well and i had the engine up to 6400 rpm at 0.6 bar with a smaller restrictor at 10.9 afr and 13° timing. then i put in the original restrictor and leaned out the mixture a little. now the mixture is around 11.3 until 5200 rpm at 0.6 bar (pulling stronger) but then starts wildly fluctuating between 11.3 and 12.9 until 5900 rpm (0.7 bar). ibpw seems unstable too. nothing weird in ve table as far as i can tell.

could this have to do with traction controll? would i see the reduction in spark when logging sparkadv? there is no change. i dont even know if car has torque reduction by throtle. maybe thats it?

any other ideas as to what might be happening. ignition related maybe?

frames 910 and 3050:

0d18.2.efi

(AD2: 0.9= 11.3 afr, 1.2= 12.6 afr)

fuel pressure is as usual btw, falling to 50 psi from 65 psi at idle (AD1).