What was found
AFTER ENGINE START, ALL OPS NORMAL IDLE PLUS OR MINUS 2 PERCENT. ADVANCED POWER LEVER TO FLY POSITION, ENGINE RPM STAYED AT IDLE 50 PLUS OR MINUS 2 PERCENT. STAYED IN FLY POSITION FOR 10 MINUTES, NO CHANGE IN RPM. BROUGHT POWER LEVER BACK TO IDLE FOR 10 MINUTES, THEN ADVANCED POWER LEVER TO FLY AND ENGINE RESPONDED NORMALLY. NOTE: AIRCRAFT WAS PARKED OUTSIDE IN BELOW ZERO TEMPS FOR OVER 3 HOURS. TEMPS APPROX 10-20 DEGREES FAHRENHEIT.