Go to auto zone and ask for a there portable engine dianostic scanner. hook it up under the steering wheel inside the car follow the instuctions and write the code down and clear the code while the scanner is hooked up. if you have an employee do it they will not clear the code. when you go back inside they will run the code and it will give you a pretty close idea of what else could be wrong. egr was replaced but it could be an O2 sensor or your exhaust manifold.