this is a 600 griz.

it will idle nice for about 20-30 sec and then it will cough and die. it will start right back up again, and if you let it idle it will do the same thing. i took it trail riding last night and it ran just fine. i just can figure out this idle cough. i have cleaned the carb completly and it found nothing. i put in a new plug and fresh gas last night. the air filter is clean.....
this quad did sit for about 3 years till about 2 months ago.
any ideas?