Hi there
..it's a bit of a long shot, but I had an experience where the bike would feel as if it was gathering itself under me, and then backfire as if to clear... turned out to be a bad earth connection, which was cured by a wire brush to all the straps... like i said it's a long shot but I was amazed that such a 'simple' thing could have such a dramatic effect
Cheers
Dano