First post here so hello guys.My f150 misses at lower rpms cruising.It's fine ideling and as soon as i give it a little go pedal but cruising it starts missing.So far I've changed plugs,wires,and coil pack and nothing has changed.It's slowly getting worse and annoying because I can't figure it out.

 

How many miles on the engine? Any check engine lights? Is it manual (standard shift) or automatic? Also have you checked the PCV Valve (right behind the coilpack)? Have you checked the IMRC levers and bushings (behind the intake manifold)? What kind of plugs did you put in (I recommend Motorcraft plugs ONLY!)?

 

223000 miles,manual and i believe it was cylinders 2 and 6 missfire codes. I haven't checked the pcv or anything else realy for that matter. I used chapo autolites.Thanks for the quick reply. I prob. won't be back on until tomorrow so I will check back then. Again thanks for the reply and any other help you may give me.

 

i have heard with these engines that nothing works right on them except motorcraft spark plugs. everything else makes weird results. i myself have never had any changed on any of my fords except on my 97 ranger i had, but that was back in 97 and i used napa plugs and they worked fine. but for some reason the 4.2L is picky.

 

i used autolights in my 02 4.2....and then got a call that my dad was in the hospital...flew to hospital..2 hour drive..ran like crap...after all the hopsital stuff was over put factory plugs back in to drive home ran like a champ...2 days later put motorcraft ...i would can the autolights for sure...

 

I've got the Autolite Finewires in... working fine ---knock on wood--- but from reading this, I might rethink and put the set of MotorCraft Finewires in...

Not having any problems... but I don't want to have to change plugs when it is -5F outside in January...

 

Same thing happened to me sorta. 72000 miles and i figured i would change the plugs as they were ori. So i figured i go with bosch plantuim 2 plugs. I had a miss after that, couldnt figure it out. An old menchinic i know told me to put oe plugs back in, so i went to ford and got what they same with from the factory. Sloved my problem. Weird huh.

 

yep, same thing with me. my 5.4 didnt like the bosch plugs i put in, now i have MotorCraft plugs and it runs great

 

Ok, thanks for all the replys. Hopefuly I'll have time to run to my local "rip you off dealer" this weekend and get some motorcraft plugs.Thanks again for all the help guys.

 

you can by motorcraft plugs almost anywhere(autozone, advanced auto, etc.)

 

You can also order them from rockauto.com for $3.45 each plus shipping. The part number is SP-504.

 

That's what I get for assuming :o. I will go that route then.

 

Put the motorcraft plugs in and still missfiring.I thought it was cylinders 2 and 6 but it's actually 1 and 6 and lean in bank 2.Could it be injectors?

 

I didn't check the irmc because I'm not sure what it is.What exactly is it and what does it do?Sorry for my ignorance just trying to learn so I can do my own work and save $110 an hour.

 

sounds like me and you are having similiar problems, ive done everything you have done as well and still having problems.....im starting to think injectors too