My seicento now starts up fine and drive perfect for about 20 to 30 mins then will not rev,, i put my foot down it kangaroos cannot hera it revving then cuts out....turn key starts again on the button standing still revs ok put it in gear start to drive off ,,the starts to kangaroo again .splatters then dies...leave for about 1 hour start it and ok to drive again for another 30 mins or so please help