I have seen flooding causing complete loss of compression on these engines several times. It was also common on Lincoln Continentals with the closely related 4.6 DOHC engine (although I have never seen it with the nearly identical engine in a Mark VIII).
Often you can get it running by cranking with the throttle held wide open (which shuts off the injectors).
Ocassionally, I have needed to pull the front spark plugs and squirt a little oil in the cylinders to restrore compression long enough to get the engine running again. It will be a little rough for a moment or two untill the other half of the engine restores compression and the oil burns off.
