I have a '99 with a 5.4L and 108K. I replaced all the spark plugs cuz it was really rough running and misfiring. Even with new plugs it's still feels like it's missing when at idle but no misfire codes or any codes at all. And my door ajar light won't turn off. (2 totally different problems but thought I'd throw it in) any ideas?

 

Check to see that EGR valve is not stuck slightly open. Check for sludge in throttle body and IAC valve. Determine if it's actually a cylinder misfire by unplugging each coil and noting the change. Go from there.

 

Thanks I'll give that a look tomorrow.

 

Try to put some wd-40 on the door switches that worked for mine my light hasn't came on since and for the running rough I'm having the same problem and I've replaced plugs coil packs maf fuel filter and checked for vacuum leaks and I still haven't found anything to fix the problem the next thing I'm gonna check is egr valve

 

Well keep me updated on it. I'll let you know what I find out to.

 

Alright will do I'm gonna test it tomorrow and also look at the IAC and see if that's the problem I'll post back when I find something

 

I checked my egr and that was good so I cleaned the IAC and it runs great now got all my power back hope this helps

 

Jeka.....I just bought a 2000 F150 and "like a DA" i was spraying under the hood...and it runs like it is only hitting on 3 cyl.....took it to a guy tonight....sprayed it 3 days ago...thought it would have dried by now????....could mine be the egr got wet?...not sure what the crap happen!!!!

 

You could have some moisture in the boots or COPs I would look at those first

 

the door ajar light is a problem on a lot of fords. My dads ranger has the same problem. You can try what someone else said about spraying some oil in there cause it's a switch that's sticking. Or you can pop your door panel off and replace it. I read somewhere that spraying oil in the door from the outside doesn't help, and you have to take the door panel off to get oil on the switch where it would actually make a difference but I haven't done it yet so I can't say for sure.

It's not an expensive part if you want to replace it.