Also, make sure you didnt oil the K&N too much (if it wasnt oiled from the factory that is), common problems with alot of filters being too oiled up, doesnt want to run that good - especially idle. Also, on the premix, you dont need any mods to run a different premix, everyone had their preference, if its free take it, just keep in mind it MAY change your stance on jetting (lean it up or richen it up).
Eric