300D won't turn off

[kenstfelix]

I know this has been discussed before, but I'm wondering what I should do next in my case. My car won't shut off when I turn it off. The vacuum lines all look fine. The door locks work fine if that's any indication of vacuum issues. I hadn't been messing around under the hood just before this happened (this happened a long time ago after I had been messing around and the brown vacuum line had come loose).

Any idea what to check next? Thanks!