I purchased a used Troy bilt tiller from an estate sale. It had not been used for along time and did not start. I removed the smelly gumed carb and had it cleaned and rebuilt. The gas tank was also scaley and I tumbled it for a couple hours with small stones and "coke" inside, then flushed out. After reassembling I got it running it worked ok for a while but begins to surge then sometimes stall. If I catch it sometimes I can keep it going with choke or carb adjustment I can keep it running. If the motor is just started it will run indefinetly on idle or higher rpm if left sitting, but if you put it underload it will act up. Also when just driveing it not tilling if you go through a ditch up down movement or even if you shift the handles left or right very quickly it will stall. Any help would be appreciated. sorry about spelling