2006 could be either AVL or Iron Barrel, but the carb you describe is what's on an Iron Barrel engine.
You have the Mikarb 28mm carb.
If it's stumbling at low throttle opening, then you can try screwing-in the embedded angled screw about a half-turn, and see if that helps.
If not, you may need a richer needle jet or a richer throttle slide, depending on exactly what throttle opening this bog is happening at.
It would help if we knew what jets are in there now, and what elevation above sea level you are at, and what temperatures you are having, and what air filter you have.
Regarding cruising at low rpms, the bike isn't intended to cruise at low rpms. It is intended to cruise in the middle rpms.
Are you in India?