My 523SEI has developed a starting problem and hesitation/ stutter when pulling away from tickover. It seems ok once the revs have risen above 2000rpm but I think its a little down on power and just generally not as responsive as it was. The fuel consumption has gone down to 17mpg average around town. It has had a recent service with new plugs etc. I presume it is electrical. Some of the other electrics have been playing up too and I don't know if it may be related. Help!