Is it in the first gear mode that the car is jumping? If so, on this type of gearbox it does appear to be a common fault. The gear ratio is extremely close between first and second which some drivers find unusual and results in them taking their foot off the accelerator, which in turn makes the car jerk a little. Does the car behave better when warmed up?

As for the tandem pump, why has this been replaced on a car only four years old with just 50,000 miles? This, and the service, should have no bearing on the jumping and jerking.