As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED ROUGH ENGINE, ON TROUBLESHOOTING, MECHANIC FOUND THE MIXTURE LEVER ON THE THROTTLE SIDE HAS A ROUGH SPOT IN IT. FUEL METERING UNIT WAS REPLACED WITH A REPAIRED UNIT, UPON TRIMMING THE ENGINE, THE MECHANIC NOTICED THE ENGINE WAS STILL RUNNING ROUGH AT IDLE AND HAD A HESITATION WHEN ADVANCING THROTTLE FROM 1700 RPM TO FULL POWER. REMOVED FUEL METERING VALVE AND FOUND THE ARM ON THE THROTTLE SIDE HAD A ROUGH SPOT ON IT ALSO. PROBABLE CAUSE UNKNOWN AT THIS TIME. NO RECOMMENDATIONS AT THIS TIME.