Sounds like your coming off the throttle too soon in the jump, you want throttle till your back tires are just off the ground, then your car will be pointing up, when you let off the throttle, the car's nose will drop slightly.

Practice adjusting it in the air. Not only does it help you TREMENDOUSLY racing people, it looks bad ass when you do it. I love flying over someone and turning my wheels back and forth in the air while i blip my throttle...