Boat motor won't Idle

I have a 40hp oil injected outboard yamaha 1990 that I can't get to Idle. I have gone thru the complete fuel system including carbs and fuel.Now the engine runs good,but won't Idle at low Idle. Fast idle runs good.Adjusting the idle screw did not help.....Larry

[boats.net]

Check compression. Sync carb throttle linkage.

[captflossman]

carbs need to be re-synched