What was found
INSPECTION TYPE-N/A, DURING CLIMB THROUGH FL350 NR 3 ENG N1 BEGAN TO FLUCTUATE +/- 3 PERCENT THEN GOT WORSE. SHUT OFF PMC TO STABILIZE, NO EFFECT. LOST THROTTLE CONTROL OF NR 3 ENG. PERFORMED INFLIGHT SHUTDOWN AND TURNED BACK TO SDF. SECOND OFFICER NOTED NR 3 BOOST/FEED SWITCH WAS IN OFF POSITION. RESTART AT FL190 WAS SUCCESSFUL, OPERATED NORMALLY. INSPECTED ENGINE VISUALLY FOR DEFECTS, NONE FOUND.