As important as the drill motor is the auger itself, appropriate ones are availeable, but not readily.
Only a guess here, judgeing by your location I'd think your likely working hardwood. The problem you are expierienceing could very likely be a function of the leadscrew of the augers you are useing. For hardwood it should be fine thread.
A course thread leadscrew can outpace the bits ability to cut and will bog down some drills.
