As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
OWNER REPORTS THAT ENGINE NOT GOING TO NORMAL RPM AT FULL THROTTLE. FOUND FUEL/AIR MIXTURE TO BE RICH, AFTER REMOVING CARBURETOR AIR BOX FOUND PIECE OF STYROFOAM PACKING SIZE OF A DIME LODGED BETWEEN VENTURI AND MAIN FUEL METERING TUBE. REMOVED FOD AND OPS CHECK NORMAL.