Catalytic Converter help 98 ES300

Can a catalytic converter be the cause of misfires on the side of the engine its onI have misfires on bank 2 cylinders 2,4 and 6 and the car idles rough below 1000rpm I see smoke coming from front catalytic converter. already changed spark plugs did fuel cleaner and o2 sensor. I do hear a rattle from what sounds like the cat at 3000 rpm. Oil level is fine.