So i bought my 2001 f150 4x4 5.4L And the first thing i did was service it. i put new plugs in it and it is the stock plugs i put back in it (because that is what i was recommended) and i even put the new little $10 boots on that go from the plugs tp the cop now i have had a miss even before i did the plugs and it is only when i am accelerating slowly and alos happens pretty randomly. I have changed the fuel filter and put about $1000 worth of additives in it and still no result shold i spend the money for a new set of cops???? Where shold i get them at??? do they make any high performance ones???? HELP ME PLEASE I CANT STAND IT!!!

 

You see, just throwing money at it isn't the wise thing to do.
Have you checked for any stored codes?
Possible there is an injector going bad.
Possible there is a coil bad.
Your kind of problems are among the more difficult to get hold of without doing a lot of testing and checks before spending money.

 

Jordan,
A miss under load is most likely an ignition problem of some sort. The usual suspect candidate is a failed C.O.P. . They fail often due to moisture getting down in the sparkplug well and shorting the C.O.P. out. It is just plan bad design. I have replaced several over the years between my truck and my wife’s two Mountaineers.
The misfire must be sustained over a period of seconds before the diagnostics system will register the misfire and set a “Check Engine” Light for the discrepant cylinder. If you have a hard miss and you are not getting a light then you have a computer problem which can be fixed. But if you are getting a light and your computer is telling you which cylinder is missing then go ahead and change out the C.O.P. and sparkplug. It will cost you around $62.00 for the new parts.
The key to keeping your C.O.P.s alive is to keep the top of your engine dry and use dielectric grease to seal the plug to the C.O.P.
MSD, Accel and Ignition Solutions all make aftermarket C.O.P. and they ain't cheap. Except for Accel through Summit ($27.00 each which is cheaper than an OEM equivialant replacement). I have the Accels and they do what I expected them to do so I am happy. Oh yeah. Buy yourself a OBDS II tester. They cost sme dollars but they are worth it in the long run if you do your own maintenance.

 

As Marylander said, dielectric grease is key. Did you use it when you did the plug change? If not, I would go back in and load them all up, you can even load up the plug wells to keep moisture out...