your off line stumble and rich idle have nothing to do with the jets its your air/fuel mixture screws you are to far out lean them out more then you should have to turn ur idle down cause as u lean the a/f screws idle will pick up. now if it keeps burning rich after you open up the carb and idle curcuit is not being used then check your power valve make sure it is tailored to your vaccum needs. if that all seems good then start with your jets. but make sure your timeing is set where you think it runs the best cause timing can alter lean,rich conditions.