As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT ENGINE STUMBLES, ACCELERATES POORLY COLD, PRIMARILY AT TEMPERATURES BELOW +20 DEGREES WHEN ADVANCING POWER THROTTLE FROM LOWER RPM, APPROXIMATELY 1000 RPM AND BELOW, TO TAKEOFF POWER. STUMBLE SEEMS TO OCCUR IN THE 900 TO 1200 RPM RANGE. APPLICATION OF CARBURETOR HEAT IMPROVES PERFORMANCE AND LESSENS THE STUMBLE, DO NOT SUSPECT CARBURETOR ICE AS A FACTOR.