2007 90hp 2 stroke mercury idle issue

i have a 2007 mercury 2 stroke that i have been trying to get rid of a idle sneeze for a while. i am very familiar with jet ski 2 stroke motors and these outboards are very different. the motor runs completely fine every where except in neutral at idle it sneezes. i can idle across the lake for a mile and give it full throttle with no hesitation. also if i have the engine in forward gear it will not sneeze it only sneezes in neutral sometimes stalling. i have rebuilt the carbs and fuel pump, fuel filter, put new spark plugs and spark plug boots on it. i have went through the process in the service manual to adjust the idle fuel mixtures and timing. i have the idle mixture screws out at 2 1/4 turns out and it is still sneezing. another thing that the motor does is it kicks back when i try to start it sometimes. any help would be greatly appreciated.

Could be a carb not fully closed

i finally got a chance to check the throttle butterflys and they are fully closed. i checked the starter gear and the flywheel and there is some heavy wears from the kick backs. anyone else have any ideas on this. it seems to me that there is to much timing advance during start up. i have tried retarding it to the point that the idle gets lumpy and it still kicks back. i have tried stating the motor in the idle and raised idle position and i still get kick backs