figured it out , its from changing stepsperrev.

but now why am i getting this distortion based on y position ?

everyone of those diamond's sides should all be the same. but the higher its drawn it seem to be streching in the y direction and if its drawn towards the bottom it stretches in the x direction.

ive calibrated my machine and stepsprerev pretty closely, im running an adafruit v1 shield on a mega settings are 400 steps per rev with 1x multiplier, 126mm/rev.
size is 725x965 the first diamond is drawn ~170mm below the sprockets.

The distortion in the diamonds is normal, every single "polargraph" style drawing has that exact same feature. If you've ever seen any other polargraph pixel drawings, you'll see that.

Temperature, with the motorshields there's not much you can do about that other than reduce your supply voltage. You might find lower voltage doesn't allow the motors to produce the same torque at the same speeds that you're used to, but thems the breaks. A variable voltage PSU is pretty useful. I had the same issue with the sprockets slipping on hot motor shafts, even running with much lower voltage, so I switched to printing my sprockets in ABS or one of the high-temperature filaments, nylon or tglase or colorfabb XT.