hey i live in minnesota and i have the same problem it started with my k&n filter too. Now i have an aem intake same crap i think its just normal just when cold???
take out the 4 bolts that hold the bushings in then when those are out swing the bar down take sand paper and clean up the bar and the brackets. also lube the hell out of the bushing when reinstalling!
you should change your spark plugs every 15,000 miles or so. also make sure you use ngk plugs otherwise your car runs kinda messed up! hope this helped!