If you've messed with that many carbs, then I would have thought you would know you can't just change a needle out with a new one and expect it to run right. You have to readjust the carb. Come on, it's not that difficult.... if you really have rebuilt, jetted and adjusted carbs before.
You had the carb off, you need to readjust the governor also. That is likely why the throttle responds differently.