I raced my 501x for the first time last weekend and struggled over the big jumps with the car nose diving all the time

obviously leading to lack of confidence when you probably most need it...
It was complete build/set up as kit (springs/oil etc) so was a pretty sluggish all round, but having tried different approaches and different throttle/brake combos never really got anywhere. I thought it would be alot more balanced no?
I also had IB42's in the back as opposed to the lighter Lipo's but it still nose dived like mad??
Any idea's