0.4A Stepper motor vs 1A stepper motor using A4988 drivers? Motor Stalling problem

I'm having a problem with my extruder stepper motor stalling for retraction speeds over 10mm/s. I still have retraction problems so would like to increase this if possible. I don't have problems with stalling on my 0.4A X,Y,Z stepper motors.

I'm using a Greg's Wade extruder for Prusa i3 with a Nema 17 Bipolar 40Ncm 12V 0.4A Stepper Motor.

My extruder Pololu A4988 stepper driver is tuned to .16V. (Vref = I_TripMax * 8 * Rs) (Vref = .4*8*0.05 = 0.16).

Relevant settings in Marlin:

DEFAULT_MAX_ACCELERATION {1000,1000,100,10000}
DEFAULT_RETRACT_ACCELERATION 3000
DEFAULT_EJERK 5.0 // (mm/sec)


Would I have more luck with a 1A stepper motor?

Is the current rating of my motor the limiting factor to my retraction speed?