Carb Related Issue 81 KZ750 LTD

I have had an ongoing possible carb related problem and I haven't been able to find out what it is.

Right off idle, the bike hesitates, and when not fully warmed up, will almost die out. Above 1/4 throttle, the bike runs really good. The carbs have been off and cleaned in an ultrasonic cleaner two times in the last couple months. I went through all the jets to make sure there wasn't any blockage. I also shot air through all the passages on the carb I could reach.

I have tried many fuel mixture screw settings, it seems to work best at about 2 3/4 turns out from seated. But still get that off idle hesitation.

Is there anything else I can check that might be causing this? I replaced the rubber carb holders and clamps and tested for leaks, and could not find any.

Could a bad spark plug wire or other igntion component cause this?