Brakes vibrating. Help please
 

2011 Chev Silverado 1500. 3 years ago, I was towing 1996 travel trailer which was heavy. I was towing down a long steep hill and front wheels started shaking when I stepped on the brakes. I figured that the rotors overheated and warped. 2 days ago, I replaced the rotors and brake pads (power stop z36 truck & tow rotors and pads). Now the brakes or front tires are vibrating when I press the brake. Please advise.