MY CAR IS A MITSUBISHI GALANT 1996. ITS BLOWING OUT BLACK SMOKE FROM MY EXHUAST, ALSO I CHECKED MY OIL DIP STICK AND IT SMELLS LIKE GAS. WHAT CAN THIS BE. DO I HAVE TO CHANGE THE CATALAC CONVERTER? OR THE OXYGEN SENSORS? I REALY NEED HELP. CAN YOU HELP UNDERSTAND WHATS GOING ON.