What was found
(CAN) ON 2 SEPARATE FLIGHTS, THE PILOT EXPERIENCED ENGINE SURGING ISSUES DURING THROTTLE ADVANCE TO T/O POWER, JUST COMING OUT OF IDLE. IN BOTH CASES, THE FLIGHTS WERE NORMAL WITH NO SURGING AT ALTITUDE. THE FIRST EVENT WAS ADDRESSED BY REPLACEMENT OF THE FUEL CONTROL. THE SECOND EVENT TROUBLESHOOTING FOUND CONTAMINATED FUEL.