I had this code when I worked with my intake manifold a while ago. Not sure why it would be happening if you weren't. Mine was caused by a vacuum leak.
If you haven't touched your manifold, yours could be caused by faulty ignition coils?
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OFT Stage 2 tune, OFH, Works AB-M, Perrin 2.75" Intake/Silicone inlet
Kartboy Short Shifter, WC Lathewerks knob, MTEC springs
TSW Nurburgring, FIVE:AD aero kit, smoked Valenti