I have this car; its a pain to idle. Do you have a low speed needle? Its located at the left hand side of the carburettor. My first engine only had a high speed needle, which meant I couldn't tune it
It sounds like its rich, so screw it in clockwise half a turn at a time. Remember, the engine needs to be warm before you tune it, as the setting will change. You'll also have to tune it according to the weather. Also check the screws that fix the carburettor to the engine block - They can come loose and then you can get air leaks.