Brakes pulsating at near stop.

If I undersgand correctly what you mean by pulsating, your brake rotors could be damaged or uneven. My advice would be to get the rotors turned, most auto parts stores do this. I would also change the brake pads if this has not been done recently.

My 06 Sierra had the same problem and would shake violently at times. The weight of the truck and your driving are a big factor. I had the rotors turned a couple times but it would return in a couple months. I upgraded to drilled rotors because they would continue to warp. I only drove the truck 11000 miles a year. After lots of research and it returning again after the rotors and pads I had to let the truck move on to someone else. Every forum I read said it is a problem that will eventually return. Also the GM dealer claims they no nothing of this problem. Good luck.