When I'm driving and change from 1st to second then put foot straight down it like kangaroos till I let off and so it smoothly same if its parked up and pop the bonnet and rev it by hand short and sharp its like its holding back or spluttering at first. Need to change alternator tensioner as its rattely at the mo so not sure if this would affect it but its fine if you change gear and slowly go up the revs anyone got any ideas