Hi <br />my 1975 Mercury 200 20 hp has a very rough idle. Even if I adjust the idle screw you can't really discern a performance difference. Also When I try to throttle it up the engine will begin to bog. The only way I can throttle it up is by closing the choke 80% then throttling up then once throttled up opening the choke. I'm assuming when I throttle up its not getting enough gas. Thus by closing the choke I am making it draw more gas? Can someone diagnose this? Is it the fuel pump or something wrong with the carb?? Any advice suggestions appreciated. Thanks.<br /><br />Adam