Welcome to the forum!
Couple of follow up questions:
1) When you replaced the rotors and pads did you confirm the calipers are floating and not getting stuck?
2) Does it happen every time you are around that speed or only certain times?
3) Does it occur under light braking, or hard deceleration?
Steering wheel back and forth is often a sign of unevenly worn pads or calipers that are frozen or not grabbing. Warped rotors, especially the vented ones are not likely to happen unless they weren't installed correctly.
Edit: Some of the guys on the board know far more than me and they will probably chime in with more specific questions.
Last edited by Golferdude1087; 11-21-2016 at 08:30 AM..