i have 03 f150 and it has the 4.6L in it and it seems like it has no power at all. and i have a K&N air filter on it and it makes this weird noise like air is coming back out of it or something like that. it happens whenever. it doesnt have a specific point that it happens idk what it is i was wondering how to fix it i have tried cleaning it and it dosnt work. what do u thing
thanks

 

Is the check engine light on? There should be a code telling you whats up. Could be your cats are clogged.

 

Not sure what the problem is, but with my K&N drop in air filter, it does make a louder sucking noise when I stomp on the gas. That would be due to the easier airflow with the K&N filter.

Good luck!