wead eater won't stay on?

i had my unit st25c in the garage didn't use it for awhile now i have to choke it to get it running and mess with the choke to keep it running even after it warms up.half choke or no choke it dies out.i removed the carb,it's clean.i removed the plug it's clean.i replace the fuell strainer in tankk it still don't work.anybody have that same problem?
should i replace the fuel in my gas tank of unit and in gas can?