Marty...so from this we assume you are using an external Rx power supply?....
[it always assists to tell all at the onset
...is there any other curio in the setup you have not mentioned?]
You have also proved that the jitter is now in the port side
circuit, however this does not necessarily conclude that the motor from the stdb side is the culprit
as the motor only presents a profile to it's control equipment
A BAS [black art specialist] someone like DM may suggest electronic check valve thingies in the wiring as clearly an unbalanced back EMF could be the root cause of the jitter
I understand that money does not grow on
trees.......however if the motor current draw is not an issue with the 20 amp ESC & if funds permit one option is to purchase an
IDENTCAL specification ESC....by careful as mtronics offer three versions of their 20 amp marine ESC.......good luck........... Derek