My car will randomly sputter and have wild AFRs (16.5-18 on the RPD, if I pin it while it's happening the RPD says the AFRs are ~14.2 but the car still sputters and barely gets fuel) and have no power and backfire. It happens more often when it's rained recently but it's done it during dry spells too and now it's occurring more consistently. Dealership says my K&N SRI is letting water through and the MAF sensor keeps getting dirty but I pull the sensor every time it happens and the sensor is clean and the filter isn't moist. All connections are sealed.

Could it be a failing MAF sensor? Any other suggestions?

 

I've had the same problems and it was a bad map sensor. Oil is getting on it and causing the sensor to go crazy. You should pull the map and see if that's your problem. I've been told a catch can will fix that but I'm not sure.

 

Clean your maf sensor as well... when you said rain and it gets worse, maf sensor is the first thing to come to mind.

 

Well SOMEONE stopped reading once they seen rain. Read everything he said in first post

 

I did. Now I leave

Jk. OP, If you are 100% sure that the maf isn't wet then move on to something else. All it takes is a mist of water on the maf to throw it out of wack

 

I replaced my MAF sensor, which helped a bit but it did it again 10 minutes after putting it in. Started thinking it was funny that I wasn't getting any codes and realized it's the front O2 sensor because my O2 codes are deleted with my catless DP.

 

Well if you have the stock intake still reinstall it and see if the issue continues. I haven't had any idle issues in the rain or after the rain with my k&n intake. Since you said you tuned out you rear o2 its tuned, did you rotate the filter differently than how it was when you tuned the car?

 

I've had all my parts and tune on for over a year and this problem started about two months ago and got progressively worse. Filter is still at 11 o'clock like it's always been. It would sputter for maybe a second then return to normal at first then now it does it after 10 minutes and doesn't stop. O2 sensor just came in so I'll have it installed friday and I'll know for sure. It doesn't do it at idle either, only under load.