Acid32, you will find a few threads about this.
It is the nature of the design that there is a jump from idle to 2000rpm. It is the way the ignition curve is set up, so adding a fuel adjusting device is not going to fix it.
Low speed riding will require slipping the clutch together with a lower gear and more revs.
Actually once setup properly it doesn't need to be this way. However there aren't many people around that know how to do it.