I pushed the gas pedal quicker than usual and heard kind of a pop as if it had popped out of drive and then it would not move. I shifted to second and then put it back into drive and it started making a nasty rattling noise. As I picked up speed going down the road it went away, and it seemed to shift fine as I made my way up to 70 mph. I was doing 70 with no noise at all, but as I slowed down and turned in to where I was going to park it started rattling again. Any Ideas what this might be?