Thread: 1 3 5 plugs looking lean.

So today I did some preventative maintenance and changed my plugs and wires at 76K. 2-4-6 looked good, but 1-3-5 were on the white side, #5 was the worst. I know #5 usually has problems due to the manifold design.
What would cause this and what can I do? I always run either 91 or 93 due to the tune. I was also planning on putting the stock airbox back on w/ the K&N filter due to my bad gas mileage, but maybe it needs to go back on due to the lean condition? Two years ago I drove to Ocean City and got 30mpg w/ the tune and stock airbox, this summer I made the same drive w/ my home depot intake and got 26mpg. Or maybe my MAF is getting bad?
Any insight is appreciated.

Perhaps clean the maf sensor, the k&n oil is known to bugger them up. Are you still running a stock pulley? any kr?

I'm NA which is why I'm puzzled by this. Cleaning the MAF is a good idea.

What mods do you have, and which tune do you have?

I have 3800 Performances DHP NA Tune, a front PEM, and a cone air filter connected to the MAF. I just put some gumout cleaner in my fill up, and I'm going to get some electrical contact cleaner to clean the MAF. Then I'll do a plug chop and pull #5 and see what she looks like. Wouldn't I be getting a SES light if I was super lean or rich?