84 Toyota Pickup 4x4 wont turn off
 

Hi all, my truck recently started randomly not shutting down completely. It still shuts down but takes a few seconds and I can hear a rumble in the motor. My truck is in very good condition with 130,000 original miles on it. I have recently just changed the spark plug wires after compromising one on the trail. I have also just discovered an leak in the exhaust flange. Other than this the 22r is running strong no problems on the road but occasionally now when I turn off the engine. Any information would be greatly appreciated. I am most concerned with doing damage to the engine. I need to determine if i should continue driving it.
Thanks.

I don't have a good answer for you but the term I most often hear for this phenomenon is "dieseling", if that helps yourweb-searches at all.