Replace vaccum assisted ignition cut off switch

Warm engine will not cut off, I have to shut off air intake and clamp fuel line; eventually, engine shuts down. Need help trying to replace vacuum assisted ignition cut off switch, if that is the problem. Difficult to get at without knowing what needs to be removed. Think this is a result of leaving ignition swit in on position too long while repairing faulty window assembly(front passenger side). Thanks for your help, so much.