[dex3361]

It sounds as though your clutch needs adjustment. If that is what the problem is if you get the PTO going by starting the engine with it engage it will not stop when you push the clutch in (that is if you dont have an attachment on it, an attachment would provide enough drag to stop it). It is probably a simple clutch adjustment. If I didnt make myself clear let me know more details of the type of trans it is some of the 2 stage clutch standard shift act like this when they are out of adjustment.