Probably the MAF sensor. Cleaning will sometimes bandaid a dirty sensor for a while, but most of the time when we get one that has a problem, even from K&N oil, it has to eventually get replaced. We also do a throttle body cleaning service to get rid of the carbon that builds up on the back of the throttle plate, and the throttle bore. On some applications it gets bad enough to make the throttle hard to open, and I even saw one rip off a deflector that's on the bottom of the throttle plate, causing the throttle to stick!