Have you checked the valves? If diesels miss, they produce some disturbing noises. If one valve is hanging or needs adjustment, it could produce this condition under load. You are absolutely right to avoid an expensive fishing expedition! Take it piece by by piece to eliminate everything until you are certain what the problem is. Compression test? Maybe try releasing compression when this occurs. If slowly releasing compression on one cylinder has no effect, it might narrow the problem down to either a bad injector or a leaky valve. Have you checked for obvious air leaks in the fuel lines? Maybe give all the connections a tweak, especially those injector banjo fittings which tighten down on the copper washers (use a torque wrench). Do you have a shop manual?