Blowing black smoke and...
I have a '04 F-350 diesel. When the truck is pulling a grade and the RPMs are getting down to about shifting to a lower gear, the truck acts like a gas engine that has a miss, and after each miss, or hesitation, the truck belches out a cloud of black smoke. Also, once the engine is hot, if you shut the truck off, it won't restart. When it does cool enough to start, it will start in the 450 to 500 RPM range and kinda putter for a few minutes until the RPMs finally crawl into the 600 range. Then the fly-by-wire accelerator will finally kick in and you can move.