I have a 92 Tercel as my beater. It runs fine but lately I notice that a little black smoke that smells like fuel comes out of the tail pipe when you get on the gas (not alot though). You can also smell it while idling from inside the car.

Does this mean that the car is running rich? If so what can I do? Could it be a bad o2 sensor? Bad plugs?

Where should I start first?

Thanks