Loss of power, been fighting it for 2 weeks

Hey guys, long time no post.I'm trying to help my cousin with his 2003 6.0. He has deletes and a straight pipe. He brought it to a mechanic to fix a oil in water problem. They did the deletes and said it was good. One day later there was still oil in the water. The radiator was bad come to find out so they install a new one. Cousin leaves, truck pukes transmission fluid due to the lines still being loose. A few days later the truck starts missing, mechanic says bad injector so they change one. A few days later it is missing again, mechanic sees the oil my cousin points out and realized tbey didn't tighten the hp oil pump......tighten, no miss. A few months later my cousin is coming back with a 24' boat from Florida and the y-pipe blows off......you guessed it, they didn't tighten it. My cousin calls the mechanic, drops the truck off and the mechanic said he has never saw that before. Picks the truck up and it is still like the y-pipe is off. Mechanic takes a look and says the turbo is shot. Well, this is where my cousin cut ties. The only reason he brought it back all those times is so the mechanic would have to fix it for free. My cousin is by means no dummy, he's just always at work.

So, my cousin and I tear into it, this is what we done:

Pulled the turbo and polished all the vgt parts in the exhaust housing
Fixed the y-pipe because the mechanic used a cut off wheel to remove all the bolts and damaged the flanges
Installed a new gasket on the passenger side down pipe on the y-pipe
Did a boost leak check with some plugs I builtTightened up everything they touched*
Cleaned the EBP sensorUnplugged the solenoid on the turbo (solenoid is brand new) and the turbo made no boost, we did that mostly to check the wiring harness
We put it on a computer and it showed a MAF code over and over after we cleared the code. We replaced the MAF and it got to where it would accept more throttle but still falls on it's face on the top side.

So, no exhaust leaks or boost leaks at this point. We have both been searching online and we have read in to it too much I believe. Help....lol.

What's the FICM voltage?

Does this help any? I have a few pictures I took of a few of the fields.

Yep, that pretty much rules out the FICM. If I'm reading the scanner right! 12V input and at least 48V output from FICM.

Does the miss come and go?

You sure you've got the turbo seated squarely to the baby's butt?

The miss might be there once out of 5 times we run it in a day's period. All the hoses, clamps, v-bands etc are seated. I even went as far as cleaning the mating surfaces of each part before we installed each piece. Don't be afraid of asking me a question that may seem so simple it is stupid, this truck has been taken apart so many times that any stupid mistake could have been made. Any advice at this point is valued and might be tried again even though we have checked it once....even twice. The truck and engine is awesome, the mechanic work by the previous shop(s) was the doom of all of this. We truly don't know what is up or down at this point because the shop could have been feeding him a load of crap. Thanks guys, keep the ideas coming.

If you think all the bases are covered mechanically, take the engine wiring harness out and check for chaffing. The '03's are notorious for wiring problems that cause trouble on and off which will drive you nuts! LOL Like a dog chasin his tail!

No joke, that it what it feels like.....haha. It's been a rough few weeks.

Thanks guys for all the input. We found the problem and fixed it today. There was a broken wire on the MAF harness. The wire was located in the #21pin on the PCM harness closest to the cab. We wired a new connector in from Ford and it's running great. The added time fixing all the other issues paid off, the truck is much more responsive and runs a lot better

Don't have to mail payment, I'll cross the river one day this week! LOL Glad you got it up and running!