Was getting a misfire P0304 pulled all spark plugs. Code only happens when cold start. Engine light going on. Rough idle until engine warmed up. Cylinder 4 plug was black. Dry not wet. All others fine. Changed plug, fuel injector and same issue. Changed coil pack and code changed to P0300 random misfire.
I need help, what’s going on?

 

Hopefully the new coil is OEM or I would be suspicious of that. Otherwise look at the injector and coil connectors and their harnesses. Also make sure there isn't a vacuum leak with the intake manifold affecting cylinder #4.

 

Thank you! We just checked vacuum leaks, but will go back and look at the coil connectors

 

I had a similar issue with my truck last year. I ended up changing cylinder 1 coil and all the spark plugs. The spark plugs I originally bought were SP580. What was recommended to me at the ford dealer. So I put those in. They aren't the right ones. You want SP580X. Mine is a 3.5 liter but sure the engine is the same. Get these ones
These spark plugs fixed all the mis firing and brought power back to my truck completely.
Before doing this though I was recommended to try replacing the fuel pump rely module. Which I did and my truck actually ran just changing that for about a week. Then I had to replace all the spark plugs and coil. But my truck ran bad. Didn't feel like it had much power. But ran fine for about 4 months. Then I decided to change the spark plugs again, to make it a habit. That's when I came across the sp580X and it was night and day difference.

Make sure you buy all new boots for your coils and replace the coil ring that seals the coil. Can't think of the name right now, little rubber piece at the top. One usually comes with the boot when you buy it. I'd replace all spark plugs also. If you still have the issue with all spark plugs being changed and a new coil. Try replacing the relay module.