Impossible to answer that question without seeing the car. It could need a tuneup - plugs, wires, ignition coils (if any), air filter, fuel filter, mass airflow sensor, EGR service, etc. Could be any or all of the above issues. We'd be more than happy to take a look at the car and let you know what we think. Give us a call to schedule an appointment at 770-676-1100.