What was found
APPROX 2 HRS INTO FLT ACFT ENCOUNTERED MOUNTAIN WAVE EFFECT AND INCREASING AIRSPEED WHEN POWER WAS REDUCED. NR 4 ENGINE POWER ROLLED BACK TO IDLE AND WOULD NOT RESPOND TO THROTTLE. PERFORMED PRECAUTIONARY SHUTDOWN AND DESCENDED. ON DESCENT PERFORMED IN FLIGHT START, ENGINE DID NOT LIGHT OFF DISCONTINUED START AND LANDED WITHOUT INCIDENT. PERFORMED T/S, CIT SENSOR FAILED CHECK. REMOVED AND REPLACED CIT SENSOR, INSPECTED FUEL FILTERS, FOUND NO DEFECTS. PERFORMED ENGINE RUN OF NR 4 ENGINE. CHECKED GROUND AT FLIGHT IDLE AND MAX POWER ASSURANCE. PERFORMED PMC CHECK AND ACCELERATION CHECK NR 4 ENGINE OPS CHECK NORMAL. WORK WAS DONE PER ALL APPLICABLE MANUALS AND AIRCRAFT WAS RETURNED TO SERVICE.