What was found
AFTER TAKEOFF NR 4 ENGINE EGT STARTED FLUCTUATING AND STARTED TO CLIMB PAST 900 DEGREES, REDUCED POWER TO 1.29 EPR. AFTER POWER REDUCTION TEMPERATURE WAS STILL 850 DEGREES, EPR WAS LOWER (1.25) THAN OTHER J ENGINES. ACFT RETURNED TO MIA AND MADE A SAFE LANDING. ACCOMPLISHED BORESCOPE INSPECTION OF LPC STAGE 4, HPC STAGE'S 5, 8, 9 AND 15, COMBUSTION CHAMBER, HPT STAGES 1 & 2, LPT STAGES 3 & 6, NO DEFECTS NOTED PER MM 72-00-00. REMOVED AND REPLACED ENGINE FUEL CONTROL PER MM 73-21-01 PAGE 401. PERFORMED ENGINE TRIM TEST PER MM 71-00-00 PAGE 501 TEST NR 9. ENGINE TEST SATISFACTORY, AIRCRAFT RELEASED TO SERVICE.