Hi Guys i recently bought this 07 Subaru impreza wrx tr i was driving home yesterday when i was at the stop light when all off the sudden i hear like a thumping under the car i had it in neutral and the shift knob started to shake by itself all of the sudden i put it in 1st gear and it stopped and i moved up a little i put it back in neautral and it did it again any ideas what it could be thanks guys hope you can help me out