I was planting oats yesterday and the engine began to race but it lost power and quit. I waited a minute or two and it returned to idle and went but soon the same thing happened. I thought maybe it was overheating so I added anitfreeze, topped off the oil, but the same thing happened .. It happened more often on the up slope but also on down hill. I recently had the engine overhauled. The head milled. In fact the problems seemed to start soon after. I am completely at a loss.