Front-end shimmy comming down the mountain

Thanks to everyone for all the great input. Looks like I have to adjust my driving technique and will do so. I will have to see how to correctly engage the engine brake feature and use that to keep my speed constant going down hill and start at a slower speed. I have the truck being checked out at King Chevrolet in Longmont where I bought it and will discuss warped rotors, computer, torquing the wheel lugs, etc. Thanks again!! Awesome site!!