check the reeds, pull carb and try to peek into intake with a flashlight, or unbolt the intake/reedcage and have a look,
should be all 4 petals sitting tight and flat to the cage.
Set float hgt, air screw 1 1/2 turns out. Have you comepletely dissasembled carb for cleaning? Not just quick douche with spray can. I like to blow compressed air both ways through all passages. There are holes on the neddlejet/emulsion tube and a tiny one in pilot jet that must be open/clear.
Do you have fresh fuel? Preferably less than a month old?