dieseling is when a gasoline engine continues to run after electricity has been removed from the ignition circuit. The gas in the cylinders is combusting because of heat, even though there is no fire to the spark plugs, much like a diesel engine (thus it is call "dieseling" ) It can be caused by using the wrong spark plugs, improper carb settings, and some other things that are slipping my mind right now.
Thanks for the reply about dieseling, I just had a engine seize and wondered if that is what happened. It wasn't, I think the oil pump quit. Thanks for such a quick response,this site is great!!