My PSD has a miss. Took the valve covers off to determine which cylinder wasn't firing. #6 cylinder no change in the sound of the engine when I pull the injector wire off. The rest of them caused the engine to stumble even more when I pulled the injector wire off. I replaced the under valve cover harness on both sides with the newer style with integrated harness. Then ohmed the injector and that was good. Checked resistance from #6 all the way to the ECM with no breaks in the wire. Now I'm stumped. The rig only has 102K miles on it (motorhome) so I'm leaning away from a bad injector. Any thoughts?