As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
During Climbout on Flight #3380 at approximately 65% TRQ I tried to reduce Left Engine power. Initially no response. TRQ shot down to 25 to 30%. After small power applications RQ would surge to 65 to 70%. Engine was only stable between 30 to 40% TRQ. Maintenance replaced Torque sensor PN 503J177612 SN/off 51M2A608 SN/on 51M2A786. IAW CHp 74-20 Ops check good at this time.