As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MOMENTARY ENGINE ROUGHNESS/VIBRATION/ LOSS OF POWER. PILOT REPORTED:"IN THE UPWIND ON FIRST LAP IN THE PATTERN ENGINE RPM DROPPED SIGNIFICANTLY WHILE ENGINE SPUTTERED, SEEMED TO STABILIZE WITH AUX FUEL PUMP ON, DID NOT FEEL LIKE WE WERE GETTING FUEL POWER LANDED IMMEDIATELY" FUEL SERVO REPLACED.