Speaking of diesel runaway ....
My uncle (a truck driver) has on a couple of occasions experienced some slight, uncommanded acceleration while driving beside or through refineries. Apparently low hanging clouds of propane or natural gas getting sucked in the air intake. Nothing came of it, but he says it makes you feel a bit uneasy to say the least. I'd feel uneasy about the fact there is that much gas leaking, never mind the diesel problems! /forums/images/graemlins/shocked.gif
A more drastic, and terminal (to the engine), case was another relative with a GMC turbo diesel pickup. He had the turbo replaced but it must have been a poorly done rebuild and the bearings or seals or something went out. One day he started the truck, preparing to go out for the day, and it started to accelerate on its own. It was eating it's own engine oil by way of the bad turbo bearings. The faster it went, the more boost the turbo made and the worst the oil leak got. Cutting off the air supply involved tools and time and he wasn't too keen on climbing under the hood to do that, so all he could do was watch. He knew what was happening and what was to come, so he just pulled out a lawn chair and watched as the thing screamed and filled the neighborhood with smoke. Eventually it either used up all the engine oil or something just couldn't take it anymore - BANG!! and there were more pieces inside the engine than there used to be.
Lucky for him the guys that had replaced the turbo took responsibility and replaced the engine for him - about $8000 worth directly from GM.