As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT DEPARTED AIRPORT AND ENGINE BEGAN RUNNING VERY ROUGH, AIRCRAFT RETURNED TO THE AIRPORT (UNABLE TO MAINTAIN POWER OR ALTITUDE). MAINTNEANCE FOUND NR 6 CYLINDER HAD BORKEN AND BENT PUSHRODS. FURTHER INVESTIGATION REVEALED A BENT PUSHROD IN NR 2 CYLINDER. SUSPECT STUCK/STICKING VALVES CAUSED FAILURE. ALL CYLINDERS WERE INSTALLED FACTORY NEW AT ENGINE O/H ON 10/15/1999.