Brakes / Steering Wheel Feedback

My wife drives a 2000 Outback w/ 16" wheels and discs front and rear. Had some issues with shudder in the steering wheel when applying the brakes (brake pedal feels smooth). After changing all four rotors and pads, replacing the front two caliper guide pins, and getting the wheels balanced, the problem is still there. After replacing the pads and rotors, the problem was marginally improved, but quickly returned to a pretty decent shudder in the steering wheel when braking, particularly from higher speeds.

The car tracks straight when driving down the road, so I dont' feel like it is an alignment issue. I've heard about ABS sensors being dirty and causing similar conditions, but don't have anything to validate this. Has anyone else experienced similar problems? Thanks for any help.

The reason for the shudder is due to hard spots in the rotors. This occurs when the rotor is overheated, and this is caused by "sticking" calipers! I didn’t read where you rebuilt the calipers, any way this is the most common reason for reoccurring pulsations.
If the pads are not free to release after breaking then they will generate this heat and cause the hard spots.
The calipers "should" be rebuilt every time pads are replaced as the new lining will force the pistons back where contaminants have settled and cause them to bind.
I say "should" because one can "get away" without doing a caliper rebuild once or twice but it's your BRAKES! Do you REALLY want to cut corners here?
Another good investment is quality rotors the difference is in the ability to cool and metallurgy, better steel yields less hard spots.