Servo/Stepper hybrid question

Sorry if it's been asked before,I've searched and found nothing.

Building a cnc router with one servo and rest steppers. When I command the PacSci830 in serial it runs great but when I use the step/dir parallel signals needed for the rest of my steppers it runs choppy, worsening as rpm/torque increase. CNC software uses either serial or parallel but not both, so if I have to control all I need to use the parallel option.
Is this "chop" correctable within 800 Tools?

I know it seems dumb to control a servo in a stepper/open loop system but it's what was available within my budget.

Thanks for reading.

I don't know anything about your hardware but you may want to look at how many steps per rev you have setup on the servo. It sounds like the move is being broken down into small step type moves. By increasing the number of steps per rev you may be able to smooth it up. I know some of the stepper drives I have used have had a "micro-stepping" setting that would give you a multiplier to the number of steps per rev the motor was. Thats where I would start looking.