its the air screw that you should be turning in or out, generally you want to start 1.5 out, if the revs "hang" meaning it takes a bit to get back down to idle, try turning the screw in a little at a time, and if it seems to bog, go the other way. if you can't get it adjusted this way, then you'll need to change the pilot, larger if you have to go all the way in, smaller if you keep pulling it out