So I have 101xxx on my 05 F150 FX4. I started to notice a misfire when I was getting heavy on the throttle ie: getting on the highway, passing ect. I had no check engine lights or anything. So this is the series of what happened.

1)Bought some Lucas Oil injector cleaner/fuel treatment. No luck there.

2)Figured I would try a seafoam treatment. I did it through my vacuum line to the break booster and added the other half of the can into my gas tank. I got no smoke at all like all the youtube videos I watched. So I really have no idea if it worked. Well then I went to drive it, it started missing really bad and my check engine light came on. It said I had a misfire on cylinder 2.

3)Well because of the seafoam, it made the check engine light come on so at least I know I know where to go from there. I changed the plug on cylinder 2 and so far no issues.

The seafoam did not work like I thought but it did help fix my issue.

 

When did Seafoam ever work, but for wishful thinking? That's "Snake Oil" in a bottle.

 

True Dat!

 

why dont you just do all the plugs... im sure at 101k it's due for a set... you're just going to start having more and more misfires until you replace all the plugs...

 

Ford pushed the original recommendation of 100k spark plugs to 75k after the breaking issue came about