I own a 2001 non-turbo automatic transmission 2.0 liter forester. It has 104,000 kilometers on it. I recently had the oil changed, together with the oil filter, sparkplugs, airconbelt, and alternator belt. After I got it back, I noticed a throbbing sound when accelerating, with a perceptible vibration from the floor as I accelerate. This was not present before the oil change. Can anyone tell me what this could possibly be due to?