I had a similar problem with dropping like a stone. I thought I wasn't redirecting kite hard enough and found I could save the landing with a panic kite loop.
The real problem was that I was jumping way to far downwind meaning I went under the kite leaving it outside the wind window and requiring a dramatic redirect to save it.
The answer for me was to keep looking upwind at the point of take off. Body goes where head goes. So if you turn to look at the kite at point of take off you lose your edge for split second and get slingshot forward. Might not be your problem but if you feel like your not going straight up with jumps then it's worth considering.