I have a 2001 f-150 with almost 100,000 miles. It has developed a miss, mostly under light throttle. I can really feel it at 40 mph and with a very light load. 1st they replaced the spark plugs, when that didn't work they replaced the "booties". The check engine light doesn't come on but there is a definite miss. Any thoughts?

 

Completely clean the EGR passages from the pipe at the exhaust manifold right thru the EGR and thru to and clean the throttle body.
What you think is a miss is roughness from poor air/fuel mix.

 

Be advised that you may be feeling a torque converter shudder as well. Ignition misses and torque converter shudder are commonly confused for one another.

 

Thank you, it idles very smooth and always starts easily.

 

I just changed the plugs and boots on my 2002 5.4 after experiencing the same miss under light load that you describe. While changing the boots I noticed a white deposit on the copper contact in the COP of the #3 cyl. This was the same cyl. that the code indicated was misfiring. I used a small flat blade screw driver to scrape off the deposits on this and several other COP's, then cleaned with contact cleaner and let air dry. I had to do this several time until all the deposits were eliminated. Now the truck drives like new and I didn't have to spring for new COP's. I drive 105 miles round trip to work on up and down terrain and the engine purred all the way this morning, the first day after the tune-up. BTW - this was an all day job, and I woudn't recommend doing it unless you are mechanically inclined. There is a good tech article by Matt Adams on changing spark plugs on this site. Check it out!