idler wrong

Go to this page http://repairpal.com/OBD-II-Code-P0300 Should have a tech determine what is setting this code and you can locate a shop here www.repairpal.com/directory and once they determine the cause you can check prices here www.repairpal.com/estimator

This code denotes "(ignition) misfires in multiple cylinders." This is commonly caused by worn out/defective ignition coil packs on this particular car. They can run from ~$55 on up EACH (engine uses 6, one for each cylinder). Begin with the spark plugs, if you've never had them replaced. Check the coil packs after that. The way to check is to pull each one off while the car is idling, and the one you pull off that does NOT slow the idling and/or make it rougher is the bad one. In your case, you may have more than one that's gone bad. Good luck.