Just out of curiosity (and in part because i had similar issues, and was going to try a few of the things from this thread before i figured it out)
when you take the carb apart, and you take the larger jet out, theres that little silver tube that sits on top of the jet, and into the throat of the carb. if that one little peice is in upside down, it will cause issues pretty close to what you are having. when it is in the right way, it sticks out into the throat of the carb more than the other way.