When you flushed the system did you just replenish with new fluid from the reservoir via the return line? If so, I would redo by draining the system (while warm)from the lowest point in the system which would be one of the lines connected to the steering rack. Open the line and let drain, then slowly work the steering wheel back and forth (lock to lock)to purge as much of the fluid and contaminates as possible. Reconnect the line to the rack and refill the reservoir with good quality clear power steering fluid (not ATF). Start the car and slowly work the steering wheel back and forth (lock to lock)to bleed the system. Recheck the reservoir and top off. Hopefully, over a period of a couple of days the new fluid will condition the seals and steering will return to normal. Good luck.