Truck has been running good up until today, other than an occassional misfire. Was planning on changing spark plugs and cleaning the TB soon, along with some other maintenance.

Well, I started the truck today and noticed a slight miss when I put it in drive, and when I got on the road I noticed that it stuttered bad when over 2000 RPMs. Slowly got worse to the point of any pressure on the pedal, it would stutter horribly at all RPMs and the throttle wasn't very responsive.

Dealt with this for the 2 hour drive home and cleaned the TB to see if it would help any, and it didn't help much. Throttle reponse was a little better, but still the horrible stutter at all RPMs. It sounds like the engine is getting too much air, possibly a vacuum leak? Any other ideas? There was a code, but I unhooked the battery while cleaning the TB, so I am going to drive it around tomorow and hopefully the code will show back up and I can have it read.

Truck is a 2004 5.4l. Thanks.

 

I would get the sparkplugs swapped out and have the coils checked.

 

How many miles? Has the code came back yet? I would definitely change the plugs out if they have never been done.

 

102k miles with original plugs. They definitely need to be changed, it just doesn't seem be a plug problem because it ran good Thursday, and yesterday it ran totally different, and the problem is occurring at all RPMs. Going to drive it in a little bit and try to get the code to come back.

 

Considering Ford's current recommendation is to change 3v plugs every 60k, you are very overdue. With super wide gaps, anything can happen, including misfires that come and go. If you don't change them soon, you could start overstressing the coils and you will have to replace some of them too.

 

Codes were P0302 and P0316, going to change the plugs next weekend. I changed all 8 coils last summer, but I might put new boots on them while I have them off.

 

What brand coils did you put in?

 

Motorking coils off of amazon.

 

These?


It's quite possible one or more are breaking down, especially being that you are still running the factory spark plugs past their recommended service life.

 

Seems odd that it just happed all of a sudden. Bad gas I am thinking.