RE: engine tuning help?
ZDZ40RV of a newer kind, does this mean it's new or under warranty, then send it back.
Anyway I think the 2 problems have a common cause and it looks asif the fuel/mixture amount being supplied
to it isn't consistant with throttle setting wich might have 2 or 3 causes, 1) the carb, but that is unlikely because you already
replaced it and the problem aspect didn't change, or 2) ,the rotary valve or 3) always to consider
false air intake, so inspect the gaskets .