slight stutter

hi all been a while since i,ve been on all has been well untill yesterday i have 03 plate td4 auto start and drive from cold all is well turn it off could be a minute could be 5 hours starts fine but get to around 30 mph and stick to it it starts to stutter not very much but its noticeable foot down picks up straight get to around 4o 41 same again and so on only seems to happen when fethering the throttle any ideas oh its done 190000 miles all oils and filters changed every 6000 cheers