I had this happen to me when I went from Iridium plugs to NGK's. When i went back to iridiums everything went back to normal.
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09 Pontiac G8 GT
08 S2000 CR (sold)
06 Sti (sold)
98 ITR (sold)
88 civic 4 door (sold)
95 Mustang GT (sold)
87 LX 5.0 stang (sold)
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