DO NOT REDUCE THE ELEVATOR THROW!
Put an incidence meter on the wing panels (root and tip) and get rid of the warp! Turn the radio on and check the ailerons too, they may be warped. You can add a little washout if you like.
Mike's right, check that the elevators have equal travel at all stick positions, not just full up and full down. I used an MK ball bearing bellcrank to run mine but there are several ways to improve the "Y"'d pushrod.
Raising the ailerons a turn or two can help but make sure that they're straight first.
Additionally, the Cap has a high thrust line and low center of drag, it requires 1-2 degrees of up thrust on the motor. At 0 or negative the plane will balloon when you chop the throttle.
I'm on my 4th and have set up several others with ST 2300, Moki 1.35, 1.8's and 2.10's. All balanced at 25-35% of the MAC, ran +/- 45 deg. (2.5 inches) on the elevator and as much aileron and rudder as we could get. None of the above airplanes had a snap habit once the warps were straightened out. My latest even had - 1.5 deg in the left panel and + 2 deg. in the right. After I fixed it the wing rocking in high alpha stopped.

Chris