Sounds like you do well under pressure. Make your sparring matches more difficult to replicate the stress of a tourney. Start from bad positions, or give the guy a head-start on points, do not allow yourself to use your best/favorite techniques, etc, to make your self work harder.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin