We would use a Bosch rebuilt. I presume thats what you would also get from MB. Watch the prices, the Bosch one lists for about 50% more than the same thing through MB. Any good shop should know this.
We would also have a differential flow meter to absolutely prove a defficient fuel distributor. If you have had two fuel distributor problems in a short time I would check your tank for rust. Once it starts the tank must be replaced. Look at the neck where you put in the fuel. If there is white powdery deposits or, worse, red rust showing, its history.
Bosch Master, ASE Master, L1
33 years MB technician