Hello to 85mh325,
Read your post to eric ,the part about your mileage increase is not a surprise. the K&N filter works great .The oil that is applied to the filter controls the particulate matter . the filter is very low resriction . it is a fact however not hoopala, about the mass air flow sensor .Most mafs have a heated wire that sends temperature changes of that wire to the computer or pcm . the maf does not control the air flow it measures the air flow in grams of air .Most v8s have 6 to7 grams flow at 650 rpms at idle .Now the OIL from the K&N filter can get on the hot wire causing the mafs calibration or ability to register the grams of air to be innacurate causing poor mileage .That being said , The filter would have to be overoiled and K&Ns have been known to have been over oiled when new and when cleaned and re oiled.The filter media should be pink in color when oiled and not red!!! Further more most mass air flow sensors of the heated wire type have a burn off flash time when the engine is turned off to clean that heated wire only a few seconds . Sometimes though they get fouled from to much oil . Replacement time .Now no offense to anyone here ,but understanding why and how somthing works such as a mass air flow sensor is important to know especially when making changes to your engine.I am an automotive service technician and have K&N filters in a couple of my cars. Gm trucks we have in our shop with K&N filters havent shown problems ,or my customers 5.4 expedition ,so it all depends .I am careful tp oil the filters correctly . I am off topic here abit and I apologize and sorry for the long posting .
Scott of scottanlily