First find out why the throttle plates are sticking ,is the correct gasket under the carb or is the carb or gasket twisted so that they bind.
Once you get that fixed you can turn the idle screws in until you hear the idle speed drop then turn the screw out until the rpm quits increasing. there are also idle screws in the end carbs under the fuel bowls pointed straight forward in the base plate , these are usually set 1/2 turn ot from bottom & often are sealed with metal plugs over them.
