2001 Chevy Suburban

try cleaning yoru throttle plate with choke cleaner on both sides, they get gummed up and cause this. also spray in the square type hole as that is the idle control valve and try to clean that as well. it may start hard after doing this so just be forewarned. put the airduct back on and test it. if you don't know where the throttle plate is go to the tune up site on here and it's the first picture.