Possible carb issue?

I got a 2006 crf100f off some guy on marketplace as a starter bike. Bike runs well when warmed up but it's really hard to start cold without the choke on. And once the bike is warmed up it dies when idling unless I have the idle set way high. I tried adjusting the air/fuel screw but no matter if I give it more or less fuel it sounds the same and runs the same. The previous owner did say he put a new carb in shortly before I bought it, no clue on the brand or quality of the carb. He gave me the old OEM carb with the bike.