Just in case anybody stumbles upon this thread in the future hoping for answers I want to give details what I've figured out.
The Carted BBD clones are not very good. It is prone to plugging the idle circuit if it sits for any decent length of time. I just worked through this issue again. I spent a couple of days tuning and trying to get the idle set. I was starting to think I had no idea what I was doing. These are very easy to set the idle on and are fairly forgiving. I would get the idle set perfectly and it would purr just fine at 750 RPM but as soon as I would drive it it would die at stops, neutral was fine but in gear it would die. Sometimes it would even seem to be ok at a higher idle for a few hours but then it would sit overnight and in the morning it was back to not idling in gear.
I knew from past experience that if I could get carb cleaner sprayed into the mixture screw holes it would fix it but this time it didn't. It had sat for almost 10 weeks while I worked on the front end/suspension rebuild. I finally took the carb off and doused it with carb cleaner down through the metering jets, the idle ports, and through the venturi cluster. Then I used compressed air in the same spots, then carb cleaner again. Reassembled and installed. The idle was set easily and perfectly in about 3 minutes.
One thing I noticed while having trouble setting the idle was a whistling or air whine when it would get close to being right. I could make it stop this by either setting the idle speed higher opening the throttle plate, or by opening either of the idle mixtures. The problem was: doing this would make the idle wrong. When I got the idle circuit cleaned out it didn't do this. I surmise that the whistling was from the idle circuit pulling air through the venturi cluster because the fuel channel was plugged or partially plugged to the idle port.
This may be a well known thing to most people but I just wanted to complete this thread for any carb novices like me.
