What was found
(CAN) DURING CRUISE FLIGHT, PILOT SELECTED CROSSFEED FOR RT ENGINE. SHORTLY AFTERWARDS, THE RT ENGINE LOST POWER/FUEL FLOW. SELECTOR WAS RETURNED TO NORMAL, AND ENGINE CONTINUED TO RUN NORMALLY. MAINTENANCE DISCOVERED UPON INSPECTION THAT THERE WERE 2 LONG STRINGS, AND NUMEROUS BITS OF PRC SEALANT THAT CAME OUT OF THE LINE WHEN BLOWN OUT WITH COMPRESSED AIR. MOST LIKELY SOURCE OF CONTAMINATION WAS WHEN FUEL TANK MAINTENANCE WAS CARRIED OUT, AND NOT ALL REMOVED SEALANT WAS CLEANED OUT OF TANK. AIRCRAFT THOROUGHLY GROUND RUN AND RELEASED. NO FURTHER OCCURRENCE.