I have an automatic 2000 Mazda Protege with 130 000 km that I bought used, so I am not aware of maintenance history. It hesitates when idling after driving in first or second gear. When I can drive in higher gears the problem doesn't exist. I have had a tune up, spark plug change, and put fuel injection system cleaner through. Could this be an Air Intake Valve problem? If I don't have the problem fixed will it lead to greater problems in the future?