Ok here is the deal I have an 03 6.0 along with a buddy of mine. I tow a boat all the time. Well my truck was layed up for the weekend so we use his. Its the same year as mine same engine just black with a cc instead of an xtra. Both Autos. His has 134xxx mine is just around 137xxx. Anyway here is the story:
Hook the boat up to pull it to the docks, Its all down hill to the ramp from my shop so i wouldn't see this happen until the way back. We go out for about an hour or so and pull the boat back out. We come up to the 1st hill not very large and the boat is a 27 foot with small blocks weighs about 7500 as it sits on the truck. Seems to be a bit lacking but dont think much of it maybe he just isnt in the pedal. 2nd hill decnt grade about 1/4-3/8 mile long. Starts to go up the hill get to about 2500 and seems like we are draggin azz so i hear him get in to it turbo sounds there but ton of black smoke ad motor sounds like it doesnt want to turn anymore. Lets off till about 1/2 throttle you can hear the motor sounds like a diesel again clack clack clack thing and pulls ok up the hill but get back in the the pedal same thing nopower tons of smoke.
We get back to the shop slap the scanner run it for codes and get 10 of them. Prior to this he told me about a hard starting condition. if he left it for one day the truck would fire right off then shut down. it would crank for about 20 seconds of cranksing fires shuts down do it again firese chugs for a second or 2 and idles and runs finre the rest of the day.
These are the codes:
P006A: manifold Absolute Pressure- Mass or Volume Air Flow corrilation
P132B: Turbocharger/supercharger Boostcontol A Performance
P0272: Cylinder 4 Contribution or balance malfuntion
P0275: " 5" "Same as above"
P0341: Camshaft Position Sensor Circut Range/Performance
P0401: Insufficent Exhaust Gas Recirculation Flow Detected
P0603: Internal Control modulae KAM Malfuntion
P0683: Glow Plug Control Module To Powertrain Control Module Communication Circut
P2290: Injector Control Pressure To Low
P2623: Injector Control Pressure regulator/open

This is what showed up no clue what to mke of it.. Im not diesel tech by any means or know much about these. I did check Ficm M Power 47.92 is the best I can check and onthing i know to check.
Thanks
Mike

is it making any boost, it sounds like the turbo has expirede.

I agree on turbo bad

did you clear the codes then try agian? I would think if it was the turbo it would be consistant with not running correctly. He says its hard to start, then once its running it does run fine.

Sounds like its making boost i hear the turbo whistling sounds like its boosting. Once it starts seems to run fine and idle. But still lacking power when towing. Probabaly doesnt have the power it should even with nothing on the back. I never drove it but i would assume.
He did clear the codes once from what he told me and said seems more codes have come back. He rembers the turbo code the mass codes and the egr code for sure.
It had an egr cooler done and a radiator
-Mike

those codes are all over the place

id snoop around some ford forums....ask some questions. alot of knowledgable people on those. goodluck.

have ya checked the vacuum lines and such? how is the oil level? radiator fluid? fuel filter? is the fuel filter housing on good with no leaks for it suck air?

No fuel leaks vacuume line all tight seems all good. new radiator and cooland egr cooler airfilter fuel filter
-mike

How long ago since the EGR cooler was done? Sounds like the FICM issue I had TWICE. The 6.0L is bad about clogged injectors too if you don't change the fuel filters nearly as often as changing the oil.

2 months for the egr ficm looks good at 47.9 volts.