One or more cylinders may be misfiring causing vehicle to shake. An engine misfire can cause noise as it backfires. Your local repair shop should perform a diagnostic inspection of your Tune up parts. Intermittent shakes and noises could also be caused by loose suspension parts, broken mounts, driveline components such as U joints. There are too many possibilities/ components to mention to properly diagnose. For safety have your local repair shop inspect vehicle.