What was found
IN CRUISE AT 380 AIRSPEED DECREASED AND INCREASED SIGNIFICANTLY WITH NO AUTOTHROTTLE RESPONSE (ISA 1) (NO TURBLUANCE) OPTIMUM CRUISE ALTITUDE 388 THE AUTOTHROTTLES FUNCTIONED CORRECTLY IN ALL OTHER PHASES OF FLIGHT. COULD NOT DUPLICATE DEFECT. NO FAULTS LISTED LAST 15 LEGS IN A/T FAULT HISTORY. ACCOMP A/T CURRENT STATUS TEST SEVERAL TIMES. CHECK OK, NML REF MM:22 31 00. ALSO PRECAUTIONARY CHECK HGS FAULT FLT HISTORY & DFCS FLT FAULT REVIEW FOR RELATED FLT LEG ALL SHOW NO FAULTS REF SMM:34 36 00 & FIM:22 11/801.