The only thing I can think of that would make the noise you describe, at the times you say, would be the "air injection pump". This pump is part of your emissions control system. It is designed to inject fresh air into the exhaust system on deceleration to reduce hyrocarbon emissions.
If the air pump is going bad, it will make noise when it is activated on deceleration. I could be all wet here, but this is the only thing that makes any sense. You may want to have this checked out.
Sunday, April 12th, 2009 AT 5:42 PM