What may cause the reduction in the engine output power with simultaneous reduction of exhaust gas temperature and combustion pressure of single cylinder?
The fuel injection valve is faulty: nozzle clogged or needle jammed in the closed position. Strong pulsation can be felt with hand on high-pressure fuel pipe. Replace the faulty injector asap.
If no or weak fuel pulsation identified in the high-pressure fuel pipe, most probably the fuel pump failed: plunger get stuck, suction or delivery valve failed, roller with push rod damaged. Inspect and replace the subject fuel pump asap.
