[Chris Stewart]

Ahhh, the dreaded P0300-Intermittent Cylinder Misfire/all cylinders-no particular cylinder.
The fuel pressure needs to be 63-66psi.
Get rid of the K&N and get a plain paper filter...the filter oil gets on the MAF sensor and messes with the signal.

I don't know how to clean a MAF sensor if it does get oily, all help gratefully accepted.

I have a picture somewhere of dirt & oily residue on my turbo blades from using this filter on my Cummins. Dirt & residue hasn't been back since changing to paper.
You might change where you're buying fuel since it's been so rainy this year. Try to locate non-alky fuel. Exxon doesn't use alcohol here.