Your going to have to reduce the size of the idle feed restrictors. There are 2 per metering block and they are on top. Where do you live? Reason I ask is because elevation plays a big role in what size the idle feed restrictors need to be. For example I bought a quick fuel super street series 680cfm vaccum secondary carb back in july for my 360 magnum and I bolted it on and was fouling plugs and loading up at idle real bad. Even with my timing being at 16 degrees initial. I live 4000 feet above sea level, I ended up going down 4 sizes on my idle feed restrictors and that took care of my plug fouling problem and it idles real good now.