sorry for double post not sure why it did that. My brother said that its supposed to improve hp and mpg. throttle body has been cleaned recently and not sure what a maf sensor is sorry im not exactly car savvy. i know some stuff but not everything and usually anything i have to do to it, i take it somewhere to get it done. i havent had any check engine lights yet so not sure about spark plugs so far i have 56k miles approx.