I have a 2 cycle commercial 6.5 HP 21'' lawn mower problem, the idle goes up, than down goes up ,than down consistanly I have to push lever all the way to choke and the idle smooths out but it smokes alot and if it dies good luck getting it started again. what I have done so far, new carb last season ran great with this but later that year it started doing this. This year pulled carb off cleaned,installed new plug. thoughts? My thoughts I was thinking stater since it is so hard to start I don't use machine alot only about an hour a week. So it doesnt get used that much and the machine is kinda cool looking so I just can't let it go it has some sentimental value to me I started with this machine 6 years ago.