Small Engines (Lawn Mowers, etc.): craftsman riding mower, craftsman riding mower, engine speed

Question
I have a craftsman riding mower I got back from the shop a couple of months ago and now the engine won't quit running when I turn the key off. It keeps spitting and sputtering sometimes I have to engage the blade or put in gear on lowest engine speed just to get it to die....please help.

Answer
Sounds like somehow the ground to the ignition coil has been disconnected. Generally on the right side of the engine(from sitting in the seat) you will see wires going up the side of the engine toward the front. Usually a one or two will go to the carburetor and one will go in the flywheel cover to the ignition coil. When you turn the key off, or a safety swich isn't satisfied, a ground is sent to the coil to kill the spark, shutting off the engine.