To check the injectors you need a mechanics stethoscope and a NOID light. Listen for a click at each injector. Have you located the dead cylinder yet? The injector that doesn’t click is either stuck or not getting a signal. If you have one that doesn’t click, remove the connector to that injector and connect the NOID light. With engine running, the light should flash. If the injector doesn’t click, but the light flashes, you have a stuck injector.
Hope this helps.