Is this "ignition breakup"? I have did the plugs but not the wires, car has K&N filter / chopped airbox / downpipe, boost pattern is 11-8-10 but by 6500 where it stutters (it's VERY slight but noticable), it's more like 9.0-9.5 back and forth

 

check your check valves. The reason i say this is because i had ignition breakup issues likes yours @ the same RPM and my issue was a checkvalve that was reversed. Don't ask me why it caused break up. But hey.. it fixed it.

 

hmm... which check valve was it? i already swapped the one out on the pressure tank, checked the one to the vacuum chamber

 

it was the one behind the(next to the firewall) the UIM and under it. I had to pull off the UIM to get to it :T

 

ah i'll check it, it started after i installed the bosch universal o2 sensor but that shouldn't matter

 

Plug wires seems to have resolved it, however, now the car feels slower because the power is so smooth I need to check the boost pattern again, one of the leading wires was twice the resistance as the other (within spec but prolly outo f spec warm)