Without knowing anything about the bike its hard to tell really.
A well set-up standard or slighty modified bike will run sweet as a nut all day long.
My SP is a bit funny at tick-over know, but thats because it has a few mods, and is quite a 'characteristic' engine anyhow.
I would suggest you look at the basic fueling/mapping of your bike.
Does it have standard cans/chip/air filters etc.
If it does then it should run at all revs no problem.
If not then it may need setting up properly by a specialist in your area.
Throttle position sensor also springs to mind...although not to sure if that would give you the symptoms you describe?