gsxr 600 k7 misfiring at low revs

[Kev-GSXR]

Hi can anyone help?
My Gsxr 600 K7 has become sluggish and not as responsive in 1st and 2nd gear at low revs, like it might be misfiring!
However under load it flys as usual!

Many thanks

 

[ian6pot]

Difficult without hearing it but i just changed the engine on my sons Fazer and this displayed symptoms like this.It was rough and sluggish of the mark but when you opened it up it would clear. Turned out to be No.3 plug that was failing. New set in run like a dream.
When was it last serviced?