Welcome to you. Apart from the already mentioned vac leak, there is a spare connector in amongst all the wires which is the same as the map sensor connector. If you have checked all vac lines and issue remains, switch over these connections. Been there done that myself..
Hello All thanks for the warm welcome from all over. Well it was the vacuum line. for some reason the 'T' junction under the tank was making a hissing noise So I pushed them in tighter and all good. Runs like a new bike.