Do you mean it keeps running as if the key was still on or it sputters and coughs after you shut the key off?
If this keeps running then more than likely this is caused by a failed ignition switch. What you need to do to confirm this is too measure the voltage from your ignition switch while the engine is running and then shut the key off and see if you still have voltage coming from the switch. If you do, then it needs to be replaced.
If it is sputtering after you shut the key off, this is called dieseling and it is caused by fuel still entering a hot cylinder and the engine keeps "running" for a short while. However, this is most common on carburetor vehicles.
From what it sounds like, the ignition switch is you issue. Let me know what you find and we can go from there.
Monday, September 9th, 2019 AT 6:16 PM