As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IDLE SETTING WILL NOT STAY CONSTANT. IDLE CUT OFF RPM RISE VARIES FROM 300 RICH TO 50 RICH. DEPENDING ON THE MOOD EACH PREFLIGHT SHOWS A DIFFERENT SETTING. AFTER ADJUSTMENT WHILE ENGINE IS HOT. CONTAMINATION FOUND IN VENTURI, SERVO BODY AND REGULATOR.