This. Always drove me nuts because the hills by me are pretty steep (10-12⁰) and the car would be pretty aggressive in the AM with a cold motor. I always overrode by moving the shifter over before it downshifts or forcing it to upshift then back to D on flatter roads.
Does the rattle noise change with wheel speed? Or engine RPM? That would suggest something loose or broken.. or do you mean a vibration?
