When I accelerate very slowly, I can sear several successive clunks coming from the rear of the car, sometimes accompanied with a sort of groan. They are all very quiet, as I have to go slow to hear them over the engine noise. Anyone have any ideas what this could be?

 

id go ahead and pull your rear end cover. a groan is usually associated with bad rear bearings. the clunk could be a broken tooth. im guessing the broken tooth then threw out a bearing. The easiest way is to pull the cover.