2005 bonneville sputtering at low revs

I got this bike the other day and when pulling away or going at the speed you would on a round about
the bike sputters and jolts. Then the power kicks in and its fine until slowing down again.
I took it for a long ride around london. And when it got to its hottest. It was fluttering more than jolting.

Ive checked the sparks there all good ( a slight hint of white on them)
The air box and right carb was full of oil though. Im guessing the previous owener over filled it.

has any one had this problem. Or know what it could be?

thanks