Long story.
I have an 01 F250 XLT 5.4 auto 2wd. This summer it had what sounded like an exhaust leak, figured out it was #3 plug when I had the truck idling after work and it started to misfire, then shake the entire truck, then blow the plug out. The plug threaded right back in, so I ran it for a couple weeks to see if it would do it again. It did blow when I started the truck to go pick up the new plugs, took the first thread out on the plug. I checked with a borescope, and only the top thread was damaged so I installed 8 new plugs (torqued to 12 ft lbs with blue locktite) and coil packs. Roughly 300 miles later, out on the freeway #3 blew out again, this time taking the threads out with it. I unplugged the fuel injector and limped it off the freeway. Wound up buying the NOE 6003248 (adapter to run a 3 valve style plug). Truck ran great for about 35-40 miles on the freeway headed home, then started randomly missing progressively getting worse. Sounded like I was hitting the Rev limiter.
Got home and the coil boot and the new plug were both melted.
Replaced those, and discovered the cam position sensor was bad so I replaced it. Truck ran properly on my way to work. Was running on 4 cylinders after work (back two on driver's side, front and rearmost on pass side as judging by my thermal camera looking at the manifolds). 7 of the 8 came to life as it warmed up, I took it easy on the way home, hit a huge bump coming up to a stop sign and it started running on all 8 from a rolling start half throttle broke both back tires lose and the truck took off. Next stop sign 2 miles down the road it was loping like a cammed big block and that odd plug is melted again. Any suggestions before I scrap the 5.4 and install my spare 7.3 or a 460 in this truck? Right now it's parked and I'm driving my farm truck.
tr

 

With the information you've provided, why would you think that the ECU is at fault? Typically some diagnostic work is done before you declare the ECU needs to be replaced.

Have you checked to see if you have a short in the harness for the ignition coils? Damaged/melted wires? Rodent damage? How's the fuel injector harness? Checked for power and grounds? Any corrosion on the underside of the fuse junction box?

Start by finding what's not working AND why it's not working before you waste time and money throwing parts at it.

Happy Thanksgiving

-- Dave