[buildit]

Could be a vacuum leak if the vacuum hose to the front mount is leaking or the mount leaks.

Hose is visible on bottom of mount. Crawl under the front of the engine to see.

Links about front mount.
http://www.motor.com/article_pdf_download.asp?article_ID=1259

Includes picture of hose.
http://www.odysseyownersclub.com/forums/showthread.php?p=2697