When was the last time you replaced the air intake hose (circled item in photo) from the air cleaner? If you never have I would bet you have a crack in it allowing unmetered air into the engine. Take off the hose and look carefully in each "fold" for a leak. Dorman sells a replacement for the intake if you find a crack.
If there is a crack, you can patch it with duct tape temporarily (make sure the tape goes deep into the fold) and use that opportunity to confirm that is the cause of your misfire while you wait for the part to arrive.
Edit: I had a random misfire and catalyst code in my 09 Aveo. Bought a new coil pack, replaced the spark plugs, downstream O2 sensor, etc and it got a measurably better but it wasn't until I was deep into an unrelated repair and removed the air cleaner assembly that I found the crack in my hose. I suspect that was my problem all along
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BulletOriginally Posted by EAD15
When was the last time you replaced the air intake hose (circled item in photo) from the air cleaner? If you never have I would bet you have a crack in it allowing unmetered air into the engine. Take off the hose and look carefully in each "fold" for a leak. Dorman sells a replacement for the intake if you find a crack.
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