Did you ever find the source of the original debris? You need to ensure that this doesn't happen again. I've never heard of just sucking something through the intake all of a sudden. Was this the original engine in the vehicle. I have heard of replacement engines failing due to debris from the orginal engine failure getting sucked into the replacement engine. In this type of situation, the debris can even come from the exhaust into the engine due to valve overlap and such. I've seen cat convertor material inside failed engines before. I believe the EGR can also be a route for fine debris.
