I would not take any slack out of the throttle making it raise the slide personally, there needs to be a little slack at the thumb, maybe a 1/8th of an inch. You say you took it apart and cleaned it, but did you rebuuild it with a kit and measure the floats? It could be as simple as putting new components init. I orderred a rebuild kit for like $12 to $13, came with everything I needed for the carb.