Misfire at low revs/small throttle openings

I have recently acquired a 2012 Norge GT 8V just just over 3000 miles on the clock. I generally runs very well except when the revs are low and throttle openings small. Opening the throttles slightly under those conditions causes the engine to falter. There is no popping or banging and it is hard to tell if it is affecting one or both cylinders. It is just as though the ignition is being switched on and off quickly. Open the throttle further and it pulls like a train without any issues. The problem is exacerbated by the fact that here in Wales we have to ride around in 20mph speed limits. Has anyone had and then cured a problem such as this and if so, what was the cure? I appreciate there are threads on low speed misfires but I have not found anything that quite fits the issues I have with the bike.

Have the throttles been synchronised?
That sounds like the uneven running that you get on pick up with out of synch throttles.