What was found
DURING MY APPROACH TO LAND AT KILN WHEN I WENT THROTTLE IDLE, THE LOWEST MY ENGINE RPM WENT WAS 1500RPM. I DECIDED NOT TO LAND, CANCELED MY APPROACH, AND WENT DIRECTLY BACK TO BACK TO 1G0. I WAS IN CONTACT WITH TOL ATC AND THEY CONVEYED INSTRUCTIONS FROM MY CHIEF TO HOLD OVER 1G0 AT 3000 FEET AND AWAIT TROUBLESHOOTING INSTRUCTIONS. ONCE AT 1G0 I CIRCLED AT 3,000. I WAS COMMUNICATING WITH THE CHIEF AND TROUBLESHOOTING AS SHE INDICATED. I EXERCISED THE THROTTLE AS INSTRUCTED. THE LOWEST MY RPM WENT AT THIS POINT WAS 1350. THE CHIEF BRIEFED ME ON HOW THE LANDING ATTEMPT WOULD BE PERFORMED AND THAT ONCE I WAS COMFORTABLE IN THE ROUND OUT, I PULLED THE MIXTURE CONTROL TO IDLE CUT OFF FOR LANDING. ONCE I WAS ON FINAL FOR 1G0 THE RPM WENT DOWN TO 1,100 BUT DIDN'T GO ANY LOWER FROM THAT POINT ON. I PERFORMED THE LANDING AS INSTRUCTED WITHOUT INCIDENT, LANDING ON 28 AND COMING TO A STOP. MAINTENANCE COULD NOT FIND ANYTHING ABNORMAL WITH THE THROTTLE CABLE OR THROTTLE LEVER. SUSPECT INTERNAL ISSUE WITH FUEL SERVO.