ok guys i have an 02 wrx 116k miles with a full exhaust system, no cat, still have 2nd o2 sensor, an airmax intake, and stock turbo and ic. cobb ap version1 running a stage 2 tune (picked it up had that tune on it swapped to eco for a ride hated it and swapped back) , no cel, but it feels like it has started bogging or missfireing at 3500/4000 rpms and it really depends on how hard i am getting to 4k rpms if i just sluggishly get up there it doesnt start bucking till nearer 5k if i just floor it its closer to the 3.5k rpms. the only thing i changed was reset the ecu. i thought it was a fuel problem so i changed fuel filter to no avail, any ideas? tune?fuel pump/regulator? spark plugs?