Andy,
Don't try this at home... Diesel fuel under pressure can easily penetrate skin tissue and enter the bloodstream, causing injury or death.
VERY carefully with the engine running at idle loosen the injector line from the crossover tube one at a time until the sound changes, then tighten it back up. The change in sound should be the same every time, if the sound is different one time (or more) then that is the place to start. Could be the injector, could be blown o-rings on injector or crossover tube, could be bad injection pump (not as likely). If the miss only happens in the upper rpm ranges this test may not catch it. Then you are looking at pullling the injectors and having them tested at a competent shop.
Godspeed,
Trent