1981 Chevy Truck carb

Should be a fuel filter at carb, follow fuel line to carb and there at carb where fuel line is there should be a bigger nut behind the fuel line nut, first remove fuel line and then remove bigger nut and fuel filter will be inside, this is if u have carb and mechenical fuel pump, and the high idle my be do to the linkage on the outside of carb, try some carb cleaner around these areas.