What was found
DURING FLIGHT THE ENGINE RAN VERY ROUGH, BELOW 1300 RPMS AND BARELY STAYED RUNNING. MAINTENANCE TECHS GROUND RAN THE ACFT AND CONFIRMED SIGNIFICANT ROUGHNESS AT LOW RPMS AS WELL AS NO MIXTURE RISE AT IDLE. ADJUSTING IDLE MIXTURE DID NOT IMPROVE ENGINE PERFORMANCE. THE CARBURETOR, WHICH HAD BEEN INSTALLED ON THE ACFT 2.5 MONTHS, WAS REPLACED, RESOLVING THE ENGINE ISSUES.