installed new plugs & coils... still runs rough..... doesnt start right up like it used to

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your Malibu. Since you've already replaced the plugs and coils but are still experiencing rough idling, misfires, and poor gas mileage, there could be other underlying issues. The problem could be related to a dirty or faulty mass airflow sensor (MAF), vacuum leak, clogged fuel injectors, or even a faulty fuel pump. Another area to check is the throttle body—if it's dirty, it can affect performance. Running a diagnostic scan may help pinpoint the cause of the misfire and allow you to address it more accurately. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!