TYPE OF STUTTER/STUMBLE
Steady throttle/Increasing throttle/Both: stuttering from 2-3k, nearly every throttle position
MODS
Intake: Cobb short ram intake
Exhaust: Catless up-pipe, catted downpipe, catback
Engine: EJ257 Swap w/ CP pistons; 10k on build.
Fuel: stock
Turbo: stock
Engine Management: Cobb stage 2 map (OTS map w/intake)
Tuner and revision of tune(if you don't mind): n/a
MAINTENANCE
Sensors changed:knock sensor (no change)
Plugs changed: plugs changed; were very white from a lean condition. from leaking turbo inlet? (no change)
Coil Packs changed: n/a
OTHER SYMPTOMS
Check Engine Light: none
Etc: Found torn inlet, leaking bpv and tmic. Replaced inlet w/OEM, replaced bpv w/OEM, bulletproofed tmic which fixed the minor leak. pressure tested to 10psi with no leaks.
RESULTS
What has and hasn't worked for you: The torn inlet was a big problem, but stuttering still is present. Nothing has worked at this point. I am experiencing a lot of feedback knock at low throttle/low rpm which doesn't make sense. I have no knocking under WOT. I've check probably a half dozen times for something loose or bouncing around to cause the knock, but I haven't found anything.
If something worked, how long has it been working for: Nothing has worked at this point. I've been suggested to replaced my upstream o2 sensor regardless of having no codes; does that seem like a good idea? please help!