1984 Other Mercedes Benz Models smog

I have a mercedes benz 500 sec that wont pass smog. I took it to get smogged and the person told me it was misfiring and to change the spark plugs and ignition wires. The car makes a really bad smell when running. I changed the spark plugs, but problem still persists. Do I need to change the ignition wires or could it be something else?

Thank you.