First, check for vacuum leaks for the rough idle. A rough idle can come from many things. Even one cylinder can be lower in compression than the others which will cause it to have a rough idle. As far as the battery, check it for an electrical draw. Once you determine there is one, remove one fuse at a time until the draw stops. Then you will know which circuit is causing the problem. For directions to check for a draw, refer to our home page under the diy section.