As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE AT FL 390, THE AUTO THROTTLE TRIPPED OFF AND THE NR 1 ENGINE N1 SPEED ACCELERATED TO 102 PERCENT FOR 41 MINUTES. CYCLING OF THE THRUST LEVER WAS NO HELP, DESCENDED TO A LOWER ALTITUDE AND SHUT NR 1 ENGINE DOWN. AFTER ALLOWING THE ENGINE TO COOL, PERFORMED RESTART AND ALL INDICATIONS WERE NORMAL. AIRCRAFT DIVERTED TO PHX AND LANDED WITHOUT INCIDENT. MAINTENANCE REPLACED THE NR 1 ENGINE CONTROL UNIT AND OPERATIONAL CHECK OK.