To answer the question ether starting fluid or water can be used. Ether will speed rev up and water will rev down.What's the best way to locate that? I know u can use starter fluid on gas engines. But I don't know if that would be safe on a diesel?
But unless that fuel injection pump is controlled by vacuum readings I do not think that is your issue. And looking here in multiple places I do not see a vacuum read to adjust fuel metering. http://jdpc.deere.com/jdpc/servlet/com.deere.u90490.partscatalog.view.servlets.HomePageServlet_Alt
I would one at a time loosen the injector line at the injector and listen for a change in rpm. Be careful as the fuel can come out in a high pressure stream that can cause personal harm. If you hear no difference on one from the others then that is the cylinder at issue. Be it a issue with injector pump, injector and engine internals.