Your lack of power and knocking is both because the MAF sensor is oil-foulded, and is causing it to run lean, and also retard ignition to attempt to control the pinging (but the PCM can't compensate for an oiled MAF!).
I put in a K&N almost right after I bought my van, because the paper filters were plugging up in less than 10,000 miles!
Last spring, I upgraded to a MUCH larger AFE intake system, also with an oiled filter. Intake tract is clean. Engine idle is still nearly imperceptible inside the van, and it will snap your head against the headrest when you punch it (even at freeway speeds!). It hit 352,000 miles this morning.
I'm pretty convinced the V10 has no problem with oiled air filters. Just be sure to carry a can of MAF cleaner.