it looks like the cable is broke inside to me! cause when you push and pull on the throttle cable it should push or pull the slide, it should all be tight with no play!
I agree, the throttle cable needs to be dialed in right. To long or short or like darrell said broken, You will never have a good idle. I had a custom cable made for the new carb and it was just a little short, so when you fired it acted like a runaway and i had to kill imeditaly.