An air bag inside the right rear coil spring, and play around with the air pressures, start low go up 5 psi at a time until it changes back for the worse.
This is a common practice.
Another big thing would be to lower the frontend if it's too high, at least down to level with the rear if not lower.
EVERYTHING COUNTS, have the alignment checked and set the toe-out to minimum recommended, and make sure it tracks straight with the rear axle.
What front shocks and what valving rates?