UPDATE:

- no wiring issues around the accumulator... or compressor... or anywhere else that I can see or have looked.
- no fuses blown.
- replaced fuel filter. Initially, idled GREAT, and even DROVE great... then started misfiring after 3 or four minutes after driving commenced.
- Problem is less noticeable at full throttle than part throttle.
- the check engine light and wrench light HAVE NOT come back on or flashed!

I am wondering now about water or crap in fuel? Thoughts?

 

PCM then. Never seen dead cylinders primary/secondary on all 8 like that before. The coils driver would have to be screwed.

 

Grew a pair and removed the plugs. Autolite HT1's, came out in 40 minutes without issue, thank God/Allah/etc. They don't look bad, but 1 appears to have a hairline crack. Replacing all 8, see where it goes.

 

I didn't know there was Autolites in there (?) Maybe I missed that. But yea, I had the same problem before and so have others. Autolites aren't Ford spec and IF you can run them at all, they usually don't last long. In my case, they didn't last 40 miles. Lost one cylinder on the way to work and another on the way home, -barely making it. I had to temporarily reinstall my old set of Motorcrafts to use the truck. Eventually I swapped out again for a new set of Motorcraft plugs, never a problem like that again.

Yea those Autolites are the wrong heat range. Just compare resistance to a motorcraft plug, you'll see lol. What they do is heat up loosing the ability to transfer. Sometimes they get so hot that they turn colors lol.

 

UPDATE: Installed fresh set of plugs. Drove it 10 miles, drove great! Pulled up in drive, started missing again! WTH???

So, for those following, new fuel filter, drove great for a few miles and back to missing (while driving). New plugs- drove great for a few miles, started missing again (once stopped).

Let it cool, drove it again, drove great, pulled in drive, started missing.

What is the deal?

 

Could the COPs be getting hot/heat soaked and then crapping out?

 

UPDATE: Initially drove great, then missed in when put in park. Next drive, it missed while driving and quit missing in park. Thoughts??

 

More technical UPDATE: Pulled 1 COP plug at a time while running and checked voltage All but 2 fluctuated between about .4v and 2.5v.

Passenger front voltage was about .45v with no change.

Drivers rear voltage 2.08v with no change.

All voltages were taken with car in park... then for fun in drive with e-brake and driver in vehicle.

Pass front then had same voltage as others did in park.

WTH???

 

I once had a similar problem on an old Ford Ranger from th 90s. It would run fine after I changed the plugs or wires, or even let it sit for a few days, or even just clean the plugs, and then start acting up with a miss and a backfire. I never did figure out what it was, but one of the mods here told me that it was probably the PCM. I suspect that you have the same problem, it is a computer based problem and you will need to swap out the PCM to see if it goes away.

 

This thread might interrest you:
https://www.f150online.com/forums/20...ackfiring.html

 

Yea, thats what I was thinking right off. Suggested a few other things to check out first to narrow it down. But yea, all 8 coil drivers failing like that at the same time or close to just about has to be the program. I have seen plugs with the wrong heat range fail like dominoes, -however, they usually get swapped out before all 8 fail have a chance to fail. Yea PCM.

Steve93mustang - You worked your *** off on this one,but you really didn't have much of a choice. I believe these PCM's are suppose to have a 30 year life spans, under normal conditions. Whatever that is lol. I think yours is defective. Has to be IMO.

 

I ordered a set of 10 DG511 (esque) COPs from fleebay... figured 2 extra couldnt hurt. They went on this weekend and so far that has cured the misfire. I am doubtful it will work long term, but for now its running like a champ.

Thanks so much for all the assistance. If it craps itself again I will let you know!