Originally Posted by mitchmond
shouldn't it relate to car starting problem only, but not when it's moving?
The ignition switch can tell when a key is in place. When the key is in place, the electrical circuits are connected to the battery.
If you have a busted switch, the ingnition might think the key is out of the socket ... when it actually isn't. This will cause electrical failure, as if someone were to pull the plug on your car instantly. (Loose alternator cables do the same thing)
If you hear your car slowly knocking and rolling over to a stall, I'm still leaning towards the EGR.