I'm not clear what your concern is - road feel and/or not enough resistance ? Or the vehicle responds too quickly for very little input?
If the former, then follow the pressure reducing suggestions above.
If the latter, you say you've got full caster, so you've done that in the right direction, I'd check your toe-in. If it is too little toe-in or actually toe-out, that will tend to make it over-responsive as you might be describing. This is what it is often done with road race cars to make them turn in aggressively. Great on the road course, but unstable in a straight line.
