Model# 917-2736401 Engine does not stop right away when I turn off the key. I replaced the ignition switch no help.

Check the kill wire going to the coil sounds like you have break somewhere

Check all ground connections to the frame, too. The ignition module is supposed to short to ground when you turn off the key, killing spark. Try running a ground wire directly from the battery negative post to the engine case to test for a bad ground.