There is no toolpath that reliably exhibits the problem.
That's just nonsense. Up your accel and/or max velocity and try a few rapids and I'll guarantee you you'll get to the point that it will stall with monotonous regularity. The question is how little would you have to increase either to make it happen. That will give you an indication of how close you are to that point currently.
reducing my microsteps on the driver to say 1/8 which is half reduces the detail in my engraving / V carve.
Do you want to try to get to the bottom of your problem or do you want to have a reason for not trying everything I suggest? You can always put them back. BTW it's VERY arguable that your 16 microsteps is giving you no more resolution than 8 but I won't go there as I doubt you'd be convinced.
How do you turn off the toolpath display?
Take a look at the diagnostics page.