What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
According to pilot's statement: during level flight the pilot noticed a decrease in engine power without corresponding movement of the throttle. The pilot informed ATC of loss of engine power and requested to turn back and land. ATC vectored the pilot to the nearest suitable airport for landing. On downwind, the pilot reported having trouble maintaining pattern altitude and receiving ecu a and b failures. The pilot did a power off 180 to final to a landing and taxied as directed to parking. The pilot reported when in parking, the aircraft started shaking violently before engine shutdown. After engine shutdown, the pilot and ground personnel noticed engine oil covering the underside of the aircraft from engine cowling to the aircraft's tail. There were no injuries and no post incident fire or damage to airport property.
As the FAA filed it
ACCORDING TO PILOT'S STATEMENT: DURING LEVEL FLIGHT THE PILOT NOTICED A DECREASE IN ENGINE POWER WITHOUT CORRESPONDING MOVEMENT OF THE THROTTLE. THE PILOT INFORMED ATC OF LOSS OF ENGINE POWER AND REQUESTED TO TURN BACK AND LAND. ATC VECTORED THE PILOT TO THE NEAREST SUITABLE AIRPORT FOR LANDING. ON DOWNWIND, THE PILOT REPORTED HAVING TROUBLE MAINTAINING PATTERN ALTITUDE AND RECEIVING ECU A AND B FAILURES. THE PILOT DID A POWER OFF 180 TO FINAL TO A LANDING AND TAXIED AS DIRECTED TO PARKING. THE PILOT REPORTED WHEN IN PARKING, THE AIRCRAFT STARTED SHAKING VIOLENTLY BEFORE ENGINE SHUTDOWN. AFTER ENGINE SHUTDOWN, THE PILOT AND GROUND PERSONNEL NOTICED ENGINE OIL COVERING THE UNDERSIDE OF THE AIRCRAFT FROM ENGINE COWLING TO THE AIRCRAFT'S TAIL. THERE WERE NO INJURIES AND NO POST INCIDENT FIRE OR DAMAGE TO AIRPORT PROPERTY.