Gentlemen, I got a problem with my stock 01 Expedition 5.4. I was getting the oil change done and had the tech change the air filter. I had been running a K&N but it was worn out so we replaced it with a paper filter. When I left the oil change place the truck started missing or shuttering during idle and acceleration. It wasn't noticeable at first but got a little worse. When I got home I checked all the connections and hoses and they appear to be good. The Check Engine light has not come on at all. I could use some advice instead of taking it to the dealer. Could it be the IAC? Thanks

 

K&N's are washable.

 

This one had been in since the truck was new. It was getting ragged after seven years.

 

Try cleaning the MAF

 

I would disconnect the battery for a couple minutes to reset ECM. It has probably adjusted to the K&N and a new paper flows differently.

 

clean the MAF and replace or clean the IAC

 

Yea, if nothing else works - Try forcing a CEL. If it's getting worse, you'll get one eventually, but if you push the motor when it's missing or acting up, - you could force a Check Engine Light.

 

or just use a good scan tool and check the pending codes

 

you could also pop the hood and see if any oil was spilt on the engine passenger side of the engine. that and you may want to pull the front coil to look at it to make sure its dry. i know walmart near me was good at destroying coils by spilling oil on them and then spraying the oil off the engine with whatever.

 

Thanks guys. I replaced the MAF and no difference. I disconnected the battery and pulled the computer. Nothing changed after resinstalling and driving it more. I think i'll try the IAC and keep looking for something disconnected. If that doesn't work then I'll change the plugs and COPs; it about due anyways. I'll let you know if I get lucky. Thanks

 

Your right. I should do that next. Thanks