This is my first time and hoping I can findsome help. I have a 1998 F-150, 4.2 V6 4X2. Had codes pulled and replaced O2 sensors, coil pack, plugs and wire and still getting a misfire on #5. Check engine lights starts to blink when moving between 40 - 55 mph. Stops blinking when I hit 60 mph but light is still on. When light blinks truck starts to shake (running rough). It idles real good, problem is only when moving. Any help will be grealy appriciated. Thanks

 

Did you replace the correct wire? I'd replace all 6.

 

I had a similar problem when a Bosch plug went bad after 20,000 miles. Real pain the rear to diagnose, but replacing the plug fixed it.

Also, if the problem just started after you changed all the plugs, you might double check you put the wires back in the correct order. On my '99, the order of the plug wires on the coil pack does not exactly match the way they should be hooked up.

 

Had a simular thing with mine. I put new plugs, wires and a coil on it and had a misfire when I test drove it. Mine was a bad plug out of the box (Motorcraft). Put the old plug back in and got a replacement plug on warranry, didn't cost anything.

 

Yes yes and yes....LOL...I am 100% sure I did what y'all have said. But once in a while I do get that sickness CRS "Can't remember S***......LOL. Yes guys I marked all the wires and did one at a time. I'm pretty sure that I did put all the wires back in the same place cause if I didn't wouldn't I get a misfire on more then one cylinder? I think jgger might be right. I might have a bad plug right out of the box or coil pack or wire. Will have to eliminate one at a time. But before I do that, I put the old coil pack back in and getting ready to take a new code reading and see if I get same reading. Thanks guys for your input. Hope someone else might come up with any other ideas of possible cause. OHHHHH and by the way, the new coil pack was a "Standard" brand. It did not have the cylinder numbers on the pack like my old one did which was "Motorcraft". Does anyone know if they are compatible???