why does car drive rough

Hello, engine speed goes up and down typically due to an engine performance problem, often caused by a lack of or abundance of air getting into the engine when the opposite is desired. Fuel and spark can affect this as well, but it seems like air is the biggest culprit of an idle rolling situation. This can be caused by various components or even a vacuum leak. As far as the engine making loud noises -- this could be a much bigger problem. Best to have a trained ear from a local technician hear your noise and weigh in as far as what the best first step of diagnosis and repair is. Good luck.