Hi Guys

I have a problem with my b210 , it does not idle smooth, if i keep the idle higher it will stay for sometimes and suddenly rpm drops and engine stalls,when idling its rpm goes up and down a little , i have cleaned the whole carburetor Everything looks good including float level vacuum hoses etc , while driving no knocking backfiring or miss, it goes perfect but cant keep idle unless keep the leg on the gas pedal little higher than normal,what do you guys suggest me to see, is it my carburetor door which is not closing well ?if so how can i bench test it ?

thanks
regards
sumith