If you are running a normal 2.25 diesel then start with checking the pressure that the injectors pop off at. They should be set at 130/135 bar, this is assuming you have access to a pressure setting pump. It is as simple as setting a tappet to adjust them. Do not rely on so called professional outfits to get it right, I have had a set of 4 vary from 120 to 165. Once this is done set pump timing as book with a dial indicator on number one exhaust valve fully open. If not perfect try advancing the pump about a millimeter at a time, be sure to slacken the unions on the pipes to injectors when moving the pump.