Cadillac Repair: emissions problems, auto parts store, cat converter

Question
1993 deville. failed emissions test. replace cat. converter, spark plugs, ignition wiring, rotator, cap, fuel screen, ERv valve and control. still failed test. told to drive car hard to "clear" system and retest. What's left? Could fuel injectors be problem?

Answer
IS or HAS the check engine light ever illuminated on the dash ?. If NOT, Go into any auto parts store and ask for a can of TOP ENGINE CLEANER or similar product and follow the directions on the can and after a few days take it back for emissions testing.