A bad injector can make an awful knocking sound. I'd get it running and give a listen. Then, loosen the fuel line nuts on the injectors, one at a time, just enough to relieve the pressure. If you hit the bad one the knock will go away.
(Oh, she types a lot faster than I do...)
The Constitution needs to be re-read, not re-written!
If you can't handle Dr. Seuss, how will you handle real life?
Current oil burners: MB GLK250 BlueTEC, John Deere X758
New ride: MB GLS450 - most stately
Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510