Carter BBD questions

I have a stock '70 Duster that I just did a 2bbl conversion on. I put a Carter BBD on it, the one with the stamped steel cover over the metering rods. I bought it here as a rebuilt carb. I did take it apart and everything was new, checked the float level and adjusted it. It runs great, idles perfect, cruises perfect. The problem I'm having is you can feel in the throttle about halfway there is a spot with resistance, pass that spot it spits and sputters terribly. I have adjusted the metering rods, if you lower them it makes it worse. I have them adjusted all the way up, but they are now hitting the plate the covers them.

The strange thing is it feels more like a ignition problem, but it runs fine until you hit that spot in the throttle, and nothing was changed on the ignition. It will not do it while revving the engine in park. It ran fine with the 1bbl on it. I will have to say that I've always had Holley's and have never messed with Carter.

Any ideas?