Air/fuel mixture on a Rochester Quadrajet carburetor?

[dmcclanahan]

I think I have a problem with my Rochester carburetor. I think that I'm not getting the right fuel/air mixture. I'm not having a problem at start up, the problem it when I’m running down the highway. When I let me foot off the accelerator the engine sounds like it an eighteen wheeler down shifting. It makes me think that I'm not getting the right amount of air. Can I get some help?