Why is my mirage idling so rough

Hello, it sounds like you may have an engine performance issue that even could be occurring intermittently. Having the vehicle tested to check the operation of the fuel delivery, ignition spark, air intake and emissions systems is a good start to finding out what is going on with your vehicle. Additionally, when your air conditioning system turns on for example, even to defog your windshield when it's cold out, it could cause excessive load on the engine and expose any weaknesses - causing rough running. In the end, the best thing to do is have a professional experienced technician look at the vehicle and find out what is going on. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops