boat will not idol down,85hp force motor

[daveski1964]

1986 force motor will not idol down.runs three quarter wide open.i just got boat back from boat shop ,had carbs clean and rebuild,picked up boat run fine ,now boat will not idol down 3/4 wide open,boat has been at shop for a month now,he has been threw all electric ,coils power packs,stator,said there is know reason it shouldn't run ,but he can't figure out.... ANY HELP

 

[foodfisher]

Start with the idle speed adjustment screw. Bottom of timing tower.