Well, really it sounds like a matter of you hitting the throttle in the air. You're basically doing an inadvertent panic rev, which will bring the rear down and the front end up... just wait till you hit before hitting the throttle, spinning the tire in the air won't make you get to the landing any faster, at least not the way you want to get there. You're already falling as fast as possible. Also try moving forward a bit, but I really think this is more about your hitting the gas in the air, and being on the gas to clear the jump and downside shouldn't really affect it unless you're holding the gas the up the face, and then keep holding it on once you've left the crest.