I had quit smoking in feb this year my problem is that whenever i tried to get my throat clear i found few(1-5) dark spots in clear phlegm,which get destroyed when touching recently have pft done all values are normal please suggest?

PFT are to check for the function of your lungs and not to diagnose any specific disease. You ought to show what you are describing to your lung MD and have the phlegm examined.

I would expect the dark sediment in the secretions to be smoke, tissue secretions and food remnants from the years of tobacco use finally being released from the tonsils and adenoid tissues as they heal and become less hypertrophied and pitted.