You know, I had that problem with an US 1000 and all told me to cut back on the elevator throw. The problem was that I did not want to do that. Now it still may be a balance problem, but my solution, THAT WORKS, is to mix the ailerons to the elevator. Up elevator and down ailerons. The more you droop them the tighter the loops without stall.
MAKE SURE YOU CAN TURN OFF this mix!!! If any head wind at all, you will ballon bad upon landing. No wind and the plane lands slower.
You will also need to turn off for good flat spins.
My two cents.......note, have three planes with twin engines, max elevator and this mix.
Twinman