Let me start by saying I am new to the diesel world. I am an ASE certified Master tech, 44 years experience, so I know I have the skill set and the tool set to fix anything on my truck. I am however not real familiar with these engines, and would appreciate some help. Here's the thing... I bought a 2004 F250 super duty with the 6.0L from a nearby Ford dealer, it was a local trade, the dealer knows the previous two owners and it was purchased there when new, so I have a pretty good service record on this one. It ran great the first day, I was impressed with the power, quietness in the cab, all around good truck. Now some times under acceleration it will have no power, I can't hear the turbo spool up, and it dumps a tremendous amount of black smoke. There is no rhyme or reason, that I can see, as to when it will happen. Seems totally random. If I put my foot in it and cause a downshift, after 20 - 45 seconds it seems to "clear it's throat" and take off like a scalded dog. I briefly scanned the ECM and found no codes! From what I have been reading I am leaning toward sticking turbo vanes / unison ring... What do y'all think?