I have 2 lean codes, bank one and right bank, what could be the cause? My car has an AEM CAI, Nology plug wires, NGK laser iridium plugs, and straight pipes from resonator back. Mazda says its the CAI and exhaust, but the car was lagging and dieing before the CAI install. It started as a misfire so I did the plugs and wires, then it jumped to too lean bank one and now the right bank as well. My MAF is also covered in oil, so I cleaned that, no improvement. There is a little oil residue in my intake tube, but the filter isnt oil based. Is it bad O2 sensors? Bad rings? Bad Vacuum leak? Before I start installing factory parts I would like some feedback. Thnx

PS. 2004 with 71xxx miles

 

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