My 56 plate CDTi 150 Auto is really lumpy at around 1700rpm, jerky and hesitant. I've checked the 3rd injector wiring - it's already had the new wiring plugs and the contacts are as new. If i accelerate hard i don't feel the jerking, just when I'm driving smoothly and gently.

It also suffers with an appalling lack of power under 2000rpm, which can make pulling out of junctions quite hairy! Being an auto, I can't get the revs up above the troublesome rev band to pull away, so just have to sit and wait for something to happen.

It's already had the EGR valve replaced in March this year, and cleaned again in May, so I doubt it's that.

So what could it be? There are no warning lights or fault codes.