Where is the air filter located?

It is in the airbox in the left front of the engine compartment. You won't be cleaning it but replacing it. The first image shows the location. To change it you disconnect the air duct (item2) from the rubber boot on the side of the box by loosening the clamp. Then pull the fastener that holds the duct in place. Move the duct out of the way and pull up on the airbox. It will release from the lower duct and the clip that holds it at the top. Now release the catches and open the housing. The filter will be inside. Replace it and clean out anything in the housing. You may want to check the lower duct as well; it is common for rodents and such to get into them and fill them with junk that hurts airflow. If the ducts are clear and the filter isn't blocked with dirt, it's unlikely to be the issue. Oh, and the plain paper filters you can get work just fine, no need to buy some expensive oiled unit when they offer no real gains on a street car.