Could be the tranny. The autos are notorious for problems. The revving, could be related to that. On a side note, when driving, putting an auto into neutral while driving, even on a hill, is not a good idea, because in neutral the motor revs more than in gear, as well as the fact that you may need the motor power if something happens (ie blowout). Its just a not a good idea, so when driving an auto just leave it in gear. The idea comes from manual trannys when trying to save gas, which even then puts more strain on the clutch and tranny. just a suggestion.
fwracer