A B767 CREW; SHORTLY AFTER LEVELOFF AT FL300; EXPERIENCED ERRATIC PERFORMANCE FROM THEIR L ENG; REQUIRING A REDUCTION OF PWR AND A RETURN TO LGAV.

Narrative

AFTER LEVELOFF AT FL300 THE L ENG ROLLED BACK AND THE ENG INSTS BLANKED MOMENTARILY WHILE PWR XFERRED TO THE OTHER GENERATOR. DURING THIS TIME THE ENG BEGAN TO ACCELERATE TO NORMAL ENG INDICATIONS. WHILE THE FO FLEW THE ACFT THE AUTOTHROTTLE WAS DISCONNECTED AND THE L THRUST LEVER WAS REDUCED. THE RELIEF PLT AND I ACCOMPLISHED THE ENG LIMIT-SURGE OR STALL CHKLIST AS WE STARTED A RETURN TO ATH. DURING THE RETURN AT PARTIAL PWR OIL PRESSURE MOMENTARILY DROPPED INTO THE RED. WE REVIEWED THE ENG FAILURE CHKLIST AND LEFT THRUST LEVER AT IDLE. THE FUEL DUMP CHKLIST WAS ACCOMPLISHED TO GET CLOSER TO MAX LNDG WT. AN OVERWT APCH TO RWY 3R ILS WAS FLOWN USING SINGLE ENG PROCS WITH THE L THRUST LEVER AT IDLE AND ENG INSTS INDICATING NORMAL. ATHENS CENTER AND APCH DID A GREAT JOB OF GIVING US PRIORITY HANDLING. ANOTHER FACTOR THAT GREATLY CONTRIBUTED TO THE COMFORTABLE HANDLING OF THIS ABNORMAL WAS THE THIRD PLT THAT IS COMMON IN INTL OPS. WITH THE COPLT FLYING AND THE RELIEF PLT AND MYSELF HANDLING CHKLISTS AND SETUP THIS ABNORMAL DID NOT SATURATE THE CREW.