Rambo Dual Y carriage with Marlin

Hi guys. I'm trying to use a dual y carriage on my Rambo. Right now I have them wired in series and connected to a single y driver. This is causing it to skip steps even at low accelerations. I would like to try splitting it so I have one stepper on the y driver and the other stepper on the E1 driver. I know there is implementation in the firmware for this but when I enable it I get a slew of errors. I am assuming this is because it is set up for the RAMPS pins. How can I assign the Rambo pins so this will work correctly? Let me know if you need any more info.

Thanks.

Okay well looking through I see that I need to add some pins in some files in order to make the e1 stepper work like the y stepper. The only problem is I don't know which pins go where and I don't want to blow a driver or something when I try this. Any idead? I'm looking in marlin.h and stepper.cpp. I am also looking in the pins_RAMBO.h.

Okay I got it 90% figured out. It was so simple I feel like a moron. I redefined the E1 pins as Y2. The problem is the motor doesn't move, it stutters. I'm sure this is another stupid thing that I messed up. Anybody have this issue before? It's not inherent to the motor, because it does it with known good motors.