What was found
(CAN) ON FLT FROM YYZ TO DELLI, 3HRS INTO FLT, NR 4 ENG ROLLED BACK TO 75 PERCENT N1 THEN RECOVERED APROX 1,500 NM FROM DESTINATION. LATER ENG OIL FILTER CLOGGED LT CAME ON THEN ENG REDUCED TO 67 PERCENT FOR REST OF FLT. DURING DESCENT NR 4 ENG SHUTDOWN. ENGINE, MANPOWER AND EQUIPMENT ENROUTE FOR ENG CHANGE.