I bought a 1999 monte carlo and the idle is a little bit rough. Its not bad but if you listen to the exhaust its not smoooth sounding at all but it runs really smooth at higher rpms. Sometimes it takes a couple tries to get it to start but sometimes it fires right up Also sometimes the engine will stumble a tiny bit while at idle. Would a tune up fix these problems, like spark plugs, air filter, spark plug wires. The engine also is noisy when cold but ive read that all 3.1 are noisy.