Thanks wvmarle.
I've attached the code to this post as it exceeds the character limit. It's largely based on Robin's easyPID program. With this code, motors A & B run as they should without any problems. The issue seems to be when gearmotor C is turned on which is connected to another arduino. I think it is interfering with the sensors which is causing motors A & B to start stuttering.
Does anybody have any suggestions on what else I could try to stop this interference?
Thanks again,
Michael
Motors_A_B_Code.ino (11.8 KB)