Well, then I would recommend watching someone faster than you on that same jump and see what they do. Every jump is different, but you should be able to coast almost any jump if you get enough speed before the jump face and get the right body position before and during the launch. Don't just let the bike toss you around, learn to move around on it more and absorb the bikes movements with your legs and arms as you maintain your center of balance.
On shifting down to 3rd: If you can catch 4th in the straight but need to scrub off some speed for the jump, I recommend getting off the throttle and downshifting to 3rd which will cause engine breaking to help slow you down for the jump and you will be in a better gear when you land after the jump. So really your not coasting, but slowing down by downshifting. Like I said, after you can manage the jump that way then you can start waiting longer before letting off and you would then downshift to 3rd and use your breaks, then let off the breaks just as you get ready to launch. This requires precise timing and you have to work up to it.
[This message has been edited by mxpaul (edited 10-16-2000).]