What was found
AIRCRAFT WAS GROUNDED: ON TAKE OFF LEFT ENGINE NUMBER 1 WAS 5 TO 7 PERCENT LOWER AT TAKEOFF POWER .BELOW 80 PERCENT NUMBER 1 THROTTLES MATCHED. AT TAKEOFF POWER LEFT ENGINE WOULD NOT ACHIEVE TAKEOFF OR CLIMB NUMBER 1 POWER. AUTO THROTTLE ON, LEFT THE NUMBER 1 ENGINE PHYSICALLY ABOUT AN INCH BELOW NUMBER 2 ENGINE. ALL OF THIS OCCURRED ABOVE 80 PERCENT OF NUMBER 1. FUEL FLOW WAS ALSO ABOUT 1500 POUNDS LESS ON LEFT ENGINE AS THIS OCCURRED. REPLACED AUTO THROTTLE SERVO PER AMM 22-31-91.