Well ive searched for about a week on why this happens and I've changed all the plugs and coils. I thought I'd post before taking it to the dealer. The last two plugs on the passenger side were loose when i changed the plugs and the 2nd to last one the tip of the electrode and about half the strap were missing; I'm guessing it sucked a little air in and went lean.

Any ideas other than that cylinder went lean and that piston is done? I don't have codes but i do have an ses light. Its missing at idle and in 4th at cruising speeds.

Its an 04 5.4.

 

You sure you don't have codes?

I'd do a compression test.

 

I mean i didnt get it scanned. I sold my scanner awhile back and haven't had time to take it somewhere. Shouldve said idont have the codes.

 

Stupid question, but did you change the plug boots as well? I had a 2002 that did the same exact thing. All of my coils were good. Changed the plugs, and found 3 torn boots. Replaced those. Still had a misfire. I had some how not fully pushed one COP all the way down and was getting a single misfire. My truck was not even showing a CEL with 3 misfires. When I changed everything and had the single misfire it threw a code. Not saying you do not have a problem elsewhere, I always just check the simple things first.