@hamiltonprops From re- reading your OP, you say that the temperature drops 20 degrees within a second or two. That would indicate it's not a "real" drop in temperature but rather a drop in the indicated (measured) temperature - unless your hot end has an insanely low thermal mass. So, yes I go for some sort of cross talk or electrical "noise". Are you sure you haven't got a bad crimp on the thermistor wiring somewhere?
@dc42 Thank you, that pointed me into the right direction.
I tried to use a different circuit for the Heatbed as the Main Vin of the board has a 6A Breaker.
The Heatbed is now switched externally by a separate Mosfet, this works perfectly, also directs some of the High Current Stuff away from the Duet.
Toshiba6600 doesn't seem to have step pulse width etc or am I missing it?
Is it " Minimum CLK pulse width CLK 2.2 μs"
Yes, minimum step-high and step-low times are both 2.2us. Strangely, the datasheet doesn't give the setup and hold times for the direction signal. That probably means they are low. So if you use T2.2 that will set all 4 values to 2.2us, which should work.
Another likely reason for your layer shifts is that your maximum speed (M203), acceleration (M201) or jerk (M566) setting is too high for the axis along which the shift occurs.
Yet another possibility is a bad connection in the wiring for the motor that drives that axis, or a fault in the stepper driver.