You can have a bad head gasket or bad intake gasket or cracked block.run compression check if all is good then maybe bad intake gasket.
it could also be injector cup on your diesel
did you find your problem with your 6.0
Looking for a Used F-350 Super Duty in your area?
CarGurus has 24,367 nationwide F-350 Super Duty listings starting at $3,000.
Search Ford F-350 Super Duty Questions
Ford F-350 Super Duty Experts