I had this on my 5.4L, imtermittent missing, a long time without the SES light.
If the SES light is on, Autozone will hook up their scanner for free. If they get a misfire code, they'll tell you which cylinder it is.
If it's not on, best bet is to dig in and check all coils, boots, and plugs.
If you have more than 50-60,000 miles on the plugs, it's a good time to change them out. There are a couple of threads here that give help on removing COPS and plugs. That helped me out a lot getting started. When you get the COPs off to get to the plugs, the bottom half of the unit is a rubber boot that you can pull off (at least on the 5.4L). The COP has a "spring" that contacts the plugs inside of the boot. If the boots are wet or corroded from being wet, or are discolored from arcing, or sometimes even if they look OK, they may be allowing the spark to arc to the metal around it. That was the cause of mine missing. Changing all 8 boots costs $25 to $30.00. Found the boots at NAPA. Don't know if Autozone carries them yet. Definitely do this if you're putting in new plugs.
Sometimes the COP might fail, but then it would probably miss continuously. Checking the plugs (clean up and check gap) and boots (clean and not discolored), and replacing boots if nothing else shows up, or when changing out plugs might fix it.

 

Forgot to add that I tried putting dielectric tune-up grease on the boots, and helped for a couple of days, then missing came back. New boots fixed it.

 

Thanks for the tip about the boots. I will invest in them and R&R myself. I am assuming that when the dealer R&R's the coil (like the last time @ $242 for 1 coil and plug!) that the new coil comes with a new boot? True?

Also, noticed that one of my coils have a yellow mark on the top. Can I assume that's the new one that the dealer replaced?

 

My brother has an 01 SD with 150,000+ miles. When you steps on it to kick it down the truck feels like the governor is kicking in. The rpms don't drop or anything, but it does pick up and go. This is mainly when it does it. It gets worse the longer the drive. He has changed the plugs already. Could it be the those boots that everyones talking about? Theres no ses lights on.

 

I spoke with a mechanic about this problem when asking for a quote on the labor for replacing all plugs and boots. (BTW - He quoted $240.00. Look at post above. Spooky.) He said that 9 times out of 10, it's the boots that are the problem if you don't have a "hard" SES light. I ordered my boots ($34 - NAPA- Part# ICB100 - 4.6L 2000) and plan to replace them soon.

Question for you experianced folks out there: Does the screw holding the coil assembly to the engine provide anything other than securing it? Meaning, once I take the coils off, can I just twist all 8 back down and give her a test drive?

I'm planning on just replacing the boots only (no plugs) and see what happens. These stories about the back two, passenger side plugs, are makin me think about my knuckles. I don't want to replace the spark plugs unless necessary.

Thoughts out there?

 

You can, they do not ground the coil or anything, But I would bolt them down so they don't vibrate loose enough to let them arc which could burn up a coil.

 

Good point LX Man! - I only meant a drive of 5 or 10 miles, max. But you are correct, better safe than pulling out the old debit card! (again!)