I have a 2002 with the 4.2 and 112,000 miles and I just bought the truck so I'm doing a tune up, I replaced spark plugs a few weeks ago, and did plug wires yesterday. Soon as I finished I drove down the road (maybe 2 miles) and it started mis firing. I didn't cross any wires as I swapped one wire at a time to make sure. So a mechanic buddy of mine told me it might be the ignition coil pack, and I replaced it and same issue it's misifiring at idle and almost imedimmedia after start I have the pack set up as
Cab
3-4
2-6
1-5
Fan
Is there anything else I can check? I checked all spark plugs last night and 2 of them was cold and covered in gas and the other 4 was warm that's why we thought the coil pack.

 

Make sure you are using Motorcraft wires and plugs.

Anything else will make this engine run like complete garbage.

Also, make sure your plug gaps are set to spec. Just don't throw the plugs in, they are usually gapped way wrong.

 

I'm using motocraft plugs and duralast wires. They didn't have motocraft in stock and i need truck running before work on Monday, so I can't wait for dealer Monday.

 

Chances are those Duralast wires are your issue. I'd suggest getting a new set next week from Ford, and simply returning those Duralasts...

 

I swapped back to the old wires I took off ( nothing wrong ran fine before just a tune up since I just bought the truck) and it's still misfiring and those are motocraft wires

 

LOL I didn't see it until I halfway started to click reply... until I re-read it and saw that was the way you saw the coil pack...

Just double check your firing order and coil pack order is like this:



It's really easy to mess this up... trust me, I know.

 

You can order Motorcraft wires from Rock Auto at less than half the price Ford wants for them. Duralast wires are junk.

You may have a couple defective spark plugs.

MOTORCRAFT WR6110 {#3L3Z12259AB, WR6080} $37.79 Wire Set

MOTORCRAFT SP504 {#AGSF34FM, AGSF34FMF4, AGSF34FMF6} Finewire Platinum Gap: .054 $3.18 Spark Plugs

MOTORCRAFT DG532 {#5F2Z12029AD} $66.79 Coil Pack

 

I agree with GLC and MF150.
When I owned a 97 F150 with the 4.2 V6, I installed Autolite plugs. That engine sneezed, wheezed, jumped, misfired, basically ran like FECES!
Also, buy MC wires as well. And check your plug wire connections to the coil like MF150 suggests. One more thing that I have had happen, check each plugs porcelain. There could be a hairline crack in one or more of them. Did you use anti-seize on the threads? If you accidentally got some on the electrodes this can cause a misfire.

 

OP, did you figure out what the problem was?

 

Depending on what you're buying, and how the checkout system calculates shipping to your address, Rock Auto could cost you more out the door. Not that Rock Auto isn't a good source. I just bought 6 quarts of Mercon V.