I just changed the plugs in my 2004 5.4L Now when I first leave the house in the morning it acts like it stumbles or misfires slightly for about 1/4 mile and then it clears up and won't do it the rest of the day. When I start it up in the morning it starts fine and idles smoothly. It doesn't do it until I start to accelerate up to speed that first time. No check engine lights or anything. Although the first day after I changed them I went to the post office and when I came back out and started it up it was misfiring for about 30 seconds and the check engine light did come on then. The scanner said a misfire had occurred in the number 8 cylinder and I cleared the code and the light has not come back on. It has been about a week since I changed the plugs. I put the Autolite plugs in it.