HELP
 

I have a 98 6.5 Turbo Diesel with 200,000 miles. PMD is relocated and injecter pump has been rebuilt. I have a miss around 3,000 rpm under moderate acceleration. If I feather the throttle it will pull through but if I stay on it the engine stalls. It restarts right away!!. No codes and been at two different shops. Any ideas on what it is would be a great help and save my sanity!!!