I have an 06 KR with a 5.4L with roughly 46k on it. Lately the motor has seemed to be running a little rough at idle. It feels like it skips every now and then but runs great. I haven't had the time to check the spark plugs yet but don't think that is it. I am going to try and change the air filter to a K&N drop-in. I just had Roush duals put on but no other engine mods, yet.
Does anyone have any ideas on what this may be?

 

Most will say not to use the K&N The oil on them is bad for the MAF sensor. I have one and have had no issues but if I were to do it ove I would stick with paper. I think over oiling them made be the problem.

 

Is there any other drop-in that you don't have to replace all the time and can recharge like the K&N?

 

Amsoil. It's a dry filter, you clean it with a vacuum cleaner or an air hose, and it's guaranteed for 100k miles. $38.