That doesn't apply in this case, an FZS600 from 2000 is equipped with carburettors rather than fuel injection. All the TPS does is advance and retard the spark timing slightly.
Cheers for all the advice.It didn't happen before the serviceWhen changing the plugs I did not spray anything in.I have just adjusted the tps and it sounds a lot better, revs are constant.Will take it out later and or tomorrow and se how it is.Balancing the carb, home job or at a professional to do it ?cheers