[mz3frs]

^+1; except I think the MAF housing is 2.5"

 

[mz3frs]

Not oiled?

The oil is what traps most of the smaller particulate in the intake charge; You're introducing abrasive grit into your engine. I wouldn't recommend running it like that.

It seems unlikely the K&N would make you throw a code, but if it is the only thing you've changed, then that's probably it. Clear the code and swap in a 'regular' filter and see what happens.