2006 Ford Taurus
Does the Cadillac converter have anything to
do with it not starting? Brand new battery,
starter and altinator
Catalytic converter would have to be extremely clogged to keep it from starting. Scan for codes and check fuel pump, filter, fuse and relay. You should be able to hear the fuel pump (buzz/hum) "prime up" when you turn the key on.
Fords and Caddies are not compatible. ;)