I just did a carb rebuild on my Mercury 150 v6 (3 carbs). Completely stripped them , Soaked in clean over night, Sprayed with air compressor and more carb cleaner. Put carbs back on and had a high idle around 1200rpm. Pulled carbs off check float levels and they were good. I did notice that one of the butterflies were slightly open. adjusted the butterfly back to normal and reinstalled carbs. Idle went down to about 700 rpm. I did put the mixture screws back to the same 1 1/2 turns I pulled them off as. Ran the boat on the river 2 times now. Runs perfect for the first hour or two or wakeboarding then the idle wants to just back up. Making it rough going in and out of gear. Boat never did this until the carb rebuild so im looking somewhere in there before I pull them back off for the 3rd time. Maybe mess with mixture screws before pulling them off again? The linkage is not getting caught up in anyway that I can see. Maybe adjustment on throttle cable or linkage between carbs? There is only one roller that stops the linkage of the carbs and it is on the bottom carb. Is the bottom linkage suposto be sitting on the roller? I will have some pictures to upload tomorrow.