you could try the other suggestions but with my experiance and it's limited but the 18" prop and the fast spool up on the gasser really made a difference. and some planes will waterfall better than others too.
how is the wing rock doing the elevators? i havn't done alot of elevators, alot of flat spins and blenders and waterfalls and KE stuff. i get some wing rock and i don't like it to much so i am going to try to cut back some weight.