Club 80-90 Forums

So my bus will fire up with no problem and it will idle but the idle is not smooth it will idle for a couple of seconds and then surges it’s up and down all the time I have played with the idle screw the mixture screw and nothing seems to happen when you pick up the revs it’s fine so don’t think it’s fuel delivery have checked for air leaks and vacuum problems but can’t find any,the pieberg 2E carb has had a rebuild kit aswell
Please can anyone shed some light on it for me or suggest anything to look for