Cavitating pump
When you hear this cavitation, do you ever open the door and see if the bottom is full of suds? When I had my Kitchen Aid, some dishwasher pods, in particular Cascade Platinum, would cause a fair amount sudsing to occur and as a result, the pump would cavitate. Generally by the final rinse the suds would be cleared out and it would be running normally. In another instance where I would notice it cavitate is when the machine was packed full. Though it would seem to sense this an add more water in small increments, until the pressure remained constant.
All the best,
Chris