1980 kz750 H1 Carbs

No vacuum leaks rebuilt jet stage 3 pods open ehshuast polished float seats diaphams new no choke she fires up no problem runs for about 5 more mins then starts to die really slowly if I twist idlle little hesitation and sputter oh and screw on top 3 turns out advance is good valves all to spec timing dead on....now what needs adjusting so it will stay idle long enough to at least sync the carbs..what part of the carbs play most factor in the idle adjustment wise thank also 1980 kz750 h1 four