Multiple cylinder misfire one aftr another

My 01 f150 supercrew 5.4 is not happy.Sat night i was drivn it startin jerkin hard.Parked it sun i read code cyl & misfire.I took coil off took plug out cleaned it bak in ran fine til today tues.I had reset code so finally service light came on i chekd it cyl 6 misfire.Parkd a few hrs started it ok for few mins then messd up again.i do notice when i cruise at like 55 it runs close to perfect when i give gas it jerks.Had cleared code now codes bak 5 and 6 both misfire.It sounds like fuel but why would it run fine aftr i messd with numb 7 .Im putting all new coils an new plugs on it.Just the way i am u think this is prob or what else to try.Dave

Dave,
These coils are so notorious for failing. They fail when they warm up - even if it's just a little warm. I've got 3 of these trucks, and I keep 2 extra coils on the shelf, because they go bad. Replacing them all in one shot will keep you from having them on the shelf, tho. The OEM ones seem to only have lasted about 7-9 years. You're on the right track bud.

Use Dialectic grease. Helps avert premature failure by reducing resistance.

Use Dialectic grease. Helps avert premature failure by reducing resistance.

...by keeping moisture out. The biggest concern with the COPs is moisture getting in the boots and causing shorts and inevitably frying the COPs. Remove all COPs, and then remove the boots and springs from all of them. Clean the boots and springs and replace any with holes or cracks in them. Let it all dry THOROUGHLY, then apply dielectric grease to both ends of the boots and reinstall accordingly. This will prevent moisture from getting in there and causing misfires.

While you're at it, make sure the fuel injector connectors are firmly attached. I've had the retaining tabs break off before and caused an iffy connection. This is corrected with some zip ties.

Great post, Blue)(Fusion. Thanks for the reminder!

Thanks for all the input.I did infact put all new coils on and new plugs as well.The problem is gone an i also did use the grease.Thanks so much

Make sure to keep a check on your plug wires... easy way to check is look under your hood in the dark while running (told a friend :loser: this once and didn't tell him "while running" well you get the point) and watch for arcing... works better on a damp night... sometimes the wires shorting out can burn up the coil packs prematurely.

Make sure to keep a check on your plug wires... easy way to check is look under your hood in the dark while running (told a friend :loser: this once and didn't tell him "while running" well you get the point) and watch for arcing... works better on a damp night... sometimes the wires shorting out can burn up the coil packs prematurely.

That really only applies to engines with distributors. The 03 5.4 has COPs so arcing will not be visible since the boot is entirely in the head until removed.

Thanks Blue)(fusion... forgot about this truck being a coil over plug... yesterday was just one of those days.

I guess that makes me the :loser: this time...