2005 Town Car "Surges"
The engine will Rev Up extremely high occasionally for no known reason. It
happens at idle right when you're about to shift out of Park. Almost as if you're
pushing on the accelerator while holding the brake.
Usually a vaccum leak or bad idle air control valve. See this post on what causes high ldle speeds. https://ricksfreeautorepairadvice.com/high-idle-rough-idle/