A car’s engine can surge for many reasons. Generally the ignition, wires, spark plugs, or the distributor rotor and cap will cause this problem. Another possibility is that your fuel filter is clogged. Injectors could also possibly be clogged on a high mileage vehicle. This is where a tune up can help your car. A vacuum leak can also cause surging problems. First inspect all hoses and fittings then around the carb or throttle body. Run the engine and spray carb cleaner on areas that could be leaking, the engine will die or speed up when you spray if there is a leak. A vacuum leak may or may not make your check engine light come on. Surging could come from a sensor problem or a leak causing the sensor to not operate correctly. It is always good to check your computer codes first if the light is on. This will help you to identify the problem area.