By hooking the breather up to the carb with out a PCV valve you created a big vacuum leak.
I agree with Stumpy after rereading your post you added a huge vacuum leak. That breather is not meant to have vacuum on it. The result you're having is the same as if you just pulled the plug off the pvc port on the carb and left it open. You need to take that off and if needed add a pvc valve.
