Could this be the fuel pump again? I changed the fuel filter, the air filter is clean and the fuel pump was replaced under warranty a few months back. If I throttle up however slowly, sometimes it does not respond and I must let it chatter away a while before throttling up again. Not looking forward to leaving it with a French dealer for warranty work. Last time it was away a month which cost me €2400 in hire, 900kms travel all for a €150 part which takes 20min to fit.