vibrating/ wobbling

I've been having an issue with my 2wd 99 chevy Astro when I apply the brakes. The car vibrates as if one of my tires is wobbling but I checked and they are all tight. I was told it may be warped rotors so I had my entire brake system from rotors to pads replaced. It still happens everytime. It was also suggested to have tires checks, I bought new tires and at the same time had the stabilizer bar and idler arms replaced. Still nothing has changed. I am at a loss at this time and don't know what else to check. Please, if anyone can help, throw me a bone.....