Some of you are going to be much more knowledgeable than I even it comes to cars. I humbly seek your wisdom. I drive an 04 Chevy Aveo with 82k miles. The exhaust has a sputtering sound when I wait for it to warm up, and today, I was outside id the cars and could hear the exhaust fluttering. Lately, when I drive over about 45, the engine is much louder than it used to be. Ideas?