Hard to say without any audio/video clips, but when I shut my engine off, there is no shudder, vibration, or otherwise bothersome noise, etc. It just shuts down quietly & smoothly.
Has this been going on for a long time, or is it just recent? Bad gas can cause rough idling, difficult starts/stops, etc. Water or contaminants in the gas can do it.
If it has ben going on for a while, it's probably not bad gas. You'd probably want to give a detailed description of exactly what happens, whether it is every time or intermittent, what mods you have, etc.