still running on 1992 Ford Explorer

engine seems to run when ignition is turned off. obviously its not but there is still fuel in piston chamber. is ther a simple fix to this issue or are there some large repair costs on the horizon?

Asked by for the 1992 Ford Explorer
How long does it run for? I am assuming that your key is out of the ignition completely.

does it sound like it is dieseling or running on? Or does it run smooth with the key out. ?
haven't timed it - just stop it by letting out clutch slowly holding brake.