What was found
ON THE 2ND LEG OF A FLIGHT, THE PILOT EXPERIENCED AN OCCASIONAL MISFIRE THAT BECAME MORE REGULAR ADJUSTING MIXTURES AND CHECKING MAGNETOS. FAILE TO ISOLATE PROBLEM SO THE DECISION WAS MADE TO DIVERT WHERE AN UNEVENTFUL LANDING WAS MADE. MX WAS DISPATCHED FOR REPAIRS. THEY CONDUCTED A GROUND RUN AND COULD NOT DUPLICATE MISFIRE. FUEL FLOWS, MANIFOLD PRESSURES AND MAGNETO TIMING AND CYLINDER COMPRESSIONS WERE NORMAL. FURTHER TROUBLESHOOTING REVEALED A COUPLE OF SPARK PLUGS THAT APPEARED WEAK. NEW SPARK PLUGS WERE INSTALLED. GROUND RUNS WERE PERFORMED AND ACFT WAS DETERMINED AIRWORTHY. SUBSUQUENT NON-REVENUE FLIGHT WAS NORMAL. NO FURTHER MX ACTION WAS REQUIRED.