It doesn't add up. The phrase you ask conotates a direct meaning but the part can not be changed separately which leads me to believe that something is misstated.
There is such a thing as a computor potentiometer. It is a mechanical trim adjustment on the outside of the EFI ECU. It doesn't come separate from the ECU. It also only affects mixture when the contacts in the throttle switch say that the throttle is closed. This is all based upon D-Jet EFI not the newer systems.
Bosch Master, ASE Master, L1
33 years MB technician