As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL39,000 DURING CRUISE, LEFT THRUST LEVER WAS NOT RESPONDING AND EPR WAS STUCK AT 1.00. HAD TO DECENT TO FL36000 TO MAINTAIN AIRSPEED. EGT WAS BEING ERRATIC PRIOR TO THAT + OR MINUS 30 DEGREES. WE WILL FILE A SUPPLEMENTAL REPORT WHEN MORE INFORMATION IS AVAILABLE.