Ford Repair: Ford F-150 Wont Stop Cranking, ford f 150, starter solenoid

Question
I have a 1989 Ford f-150 (351).  When I shut it off it will not stop cranking.  Could it be the ignitin Module?

Answer
By cranking I will assume you mean the starter is cranking the engine over.  That would be either a bad ignition switch or bad starter solenoid.  I have seen solenoids with the alternator wire attached to the wrong terminal and that will cause the starter to stay running also.  If you mean the engine stays RUNNING, I would suspect incorrect ignition or cam timing (possibly due to a worn out timing chain).  Hope this helps,
Jason