If someone told you he was getting repeatable and consistant idle at 1,600 he must be turning the engine with an electric motor, I get the best and most reliable and repeatable idle speed at about 2,300 on all my Saitos. I'm not trying to be a smart alec but the lack of responses to your question speaks volumns. As to the first question I think the low end is rich, you might try leaning it some and closing the throttle barrel a little farther, this should get you on track.