Dealer can't find problem. That's a problem in itself.
Saturday - went to drive out of drive way and up the hill.
No power. It wouldn't climb the small hill. I had to put it in reverse
and back into the driveway again.
Reved it up a few times - and was able to go.
5 or 10 minutes later it was time to climb the hills out of Nevada City towards Grass Valley, CA ..
A "wooshing" sound came from under the hood - hesitated - and lots of really black smoke poured out of the tailpipe.
I dropped to 1750 rpm (on the dash tach) and it quit - power resumed -
took it back up to 1950-2000 rpm and there it was again.
Drove it all day - as long as I kept it below 2k it was okay - if I stepped on it (drive it like you stole it my dealer says) it would happen again.
Just recently replaced both batteries - changed the oil - a week before this started happening.
Any ideas ? No codes coming up at all. Ford dealer has no idea, and of course, cannot get it to duplicate the problem. Says my truck is perfect.

 

I'd start with a can of carb cleaner, pull the EGR valve and clean it FIRST. Also, check all your turbo piping and intercooler boots for splits/leaks.

 

Coking (carbon) Deposits in Turbo and/or EGR Valve:
Coking deposits are usually a build up of unburned fuel or oil in the exhaust system and related components (valves, turbo, EGR valve). This can be caused by poor fuel quality, overfueling/leaking injectors, idling for excessive periods of time (especially in cold ambient temperatures), low engine operating temperatures, injection timing (calibration) or oil consumption. Unburned fuel usually appears as white smoke, but over time the coking condition can result in excessive black smoke. Coking depositis can plug the EBP sensor tube, foul the EBP sensor, cause the EGR valve to stick open, block the EGR cooler, plug the MAP (boost) sensor hose, or cause the variable turbo vanes to stick open (no power/boost) or closed (excessive backpressure, black smoke, popping noise, bucking). The cause of the coking issue should be identified before replacing parts to prevent reoccurance. If poor fuel is suspected, use Stanadyne Performance or Motorcraft PM-17-A Cetane Boost.
Hope this makes sense. O.o