I have a 2009 F-150 w/5.4l and I recently installed a K&N Air intake and dual (cat back) flow master exhaust. Now my problem is that I feel like it hesitates when I need to stomp it like it needs more air and when I sometime stop at a light the idle goes up and then down till it adjust.

Has anyone had this problem? don't want to spend $$$ at the dealer so they can scratch their heads and tell me that I should've kept it stock.

thanks, I would appreciate any suggestions.

 

Put the stock intake back on. You are running too lean with that K&N. Yes, you SHOULD have kept it stock.

 

thank you.

 

And clean MAF sensor since you have a Oiled Filter on it.