Another odd sound

When I'm driving around 30-40 mph and let my foot off the gas I hear a soft rattling sound. When I put my foot back on the gas either a) the rattle just goes away, b) the rattle gets faster (for a split second) and goes away, or c) there is a slight clunk and the rattle goes away. This happens as I'm driving straight and not turning. I also don't hear any rattle when the car is stopped and I rev the engine. Any thoughts?

Is this solely rattling or more like a vibration type feeling? Do you get any noise when initially shifting from PARK to REVERSE or from PARK to DRIVE?

I would say its more of a rattle. No sounds when initially shifting from PARK to REVERSE or DRIVE.

My guess would be a loose cat cover on your exhaust. I had a similar sound on my car and thats what it turned out to be. It had rusted loose and I just had it removed.