Most likely a vacuum leak. I recently fixed a similar problem. For mine, the plastic right angle piece near the driver side post MAF tube broke in two. God knows how long I was driving around like that. Fixing it with a solid rubber hose got rid of my issue.
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35% Hooper Optik | Takeda Attack CAI | F.I. HFC | Hotchkis Sway Bar | Stillen 24row | OS Giken Super Lock LSD | TK Shift Knob | EVO-R Carbon Diffuser
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