Recently I put in a drop-in air filter from K&N in my 1998 F150 4X4 4.6L. In the past week or so when I put it into drive and go for about the first 10 seconds or so it sounds like it is running hard and not getting proper air intake but it stops and runs normal and at stops when I start to go it will sometimes do the same thing. Does anyone know what may be causing this??
Thanks

 

There's a big difference between sounding like it's not getting enough and and not getting enough air. Do you sense lack of power initally?

I've never been a big fan of the K&N drop in filters. I've had these in a few vehicles and they actually decreased my fuel mileage. I have the K&N CAI for my F150 and so far it's worked out okay, i.e. same fuel mileage and no codes.