hi,
my name is Fred, I’m a new member but definitely not new to this site. I’ve been heavily searching other people’s post with regards to missfire and tried about everything that everyone recommend and still havent fix the missfire.
A little history, I purchased a 2007 Ford Expedition Max in May 2017, and in July after driving it for around 3000 kms the engine failed. I brought it to a very small private mechanic to get the engine swapped with another 5.4L 3v which came out of a 2006 F-150
the mechanic took almost 2 months to swap the engine and after picking it on my way home the truck started to stutter and got flashing CEL. I returned it to the mechanic but he simply didnt touch it and took all the way till January this year to finally get my truck back.

Now I’m trying to fix the issue myself. So far here is the list of parts and test I’ve done
- compression test, all 8 cyl tested 160psi on cold (very cold alberta fevrurary weather)
- changed all 8 spark plugs with motorcrafts
- changed all 8 COP with motorcrafts
- changed the valve cover gasket, injector gaskets, intake manifold gasket (wasn’t necessary but wanted to eliminate possible leaking oil in spark plug holes, leaky injectors or vacuum leak)
- changed the runner control valve with motorcraft
- changed any COP plug that were not clipping right with new motorcraft ones
- tested coil wiring using a test light on both the 12v and ground signal (tested ok)
- inspected the cams, all was normal
- cleaned the MAF sensor
- cleaned the intake manifold and trottle body although they were pretty clean.
The only thing I haven’t tested yet is fuel pressure

basically when I start the truck it doesnt run right. Feels like one or two cyl are missfiring. If I drive it for some time it will get much worst, I’ll start to have missfire P030X codes.
I rarely get any CEL code since it missfire so bad that I don’t want to drive it too long.
I also get some P035X codes as well sometimes
The missfire seems to be random too, sometimes its on cyl 7, sometimes 4 & 5, sometimes 3, sometimes 2 to 4 cyl are all missfiring (can tell by pulling coil plug to hear for engine changes)...

I’m starting to feel desparate, I’ve followed most advises from forums and replaced so many parts already.

Any help would be extremely appreciated! Thank you all

You have to drive it and get the codes. There could be other codes with it that you’d need to know

i know it sucks to drive a vehicle that’s running bad but you have to do it.

I’m sorry I forgot to mention I did get codes. Many times. Over the half year or so of testing it and what not I’ve received (on many occasions)
P0303
P0304
P0300
P0351
P0353
P0357
P2104
P2107
P2110


these are freeze frames, I’ve got more on the P030X and P035X pending
also, Inotice recently that a spark plug ceramic was broken on the neck part at the top. I replaced that

when I get a missfire which the CEL tells me which, I’ll switch COP but the problem doesnt go away.
The spark plugs are quite new. Since I got my truck back I must have put no more than around 100 kms on it. I also filled up with new gasoline and added some injector cleaner recently

Those are just the cel codes I wrote down on my phone, but it’s pulled a few more than that.

I should also add. When I start the truck to work on it in the morning and its sitting cold, it sounds like I might have only 1 or 2 missfire. As the engine gets warmer it starts to get worst and worst, usually after letting it idle for 15-20 min it gets to the point that it wants to stall. If I drive it and accelerate at higher speed it’ll start to missfire P0303 P0304 and will barely make it home, barely have enough power to haul its weight.

thought I could give a little follow up. After deiving it around to get some mode6 codes, now I have:
P0353
P0357
P0306

I’m wondering if anyone could shed some light as to what could make a missfire issue move around to all different cylinders?
What should I be looking for? Replacing yet more new COP or spark plugs again?