Did the problem begin after the engine replacement? If so, when....if not,when?
Do you have any idle problems when its cold?
Was the injection pump rebuilt or transfered to the (rebuilt?) engine?
Some odd problems can occur when the rack limiter screw is adjusted a bit too tight. Similar difficulties from a bad or wrongly adjusted aneroid compensator(the metal thing on top of the injection pump that the boost line connects to).
Even when they were new some of the 617.95 Turbodiesels were real pigs from a dead stop when cold.
ASE Master Tech
Mercedes Tech 19 Years