I had a similar problem when I had my transaxle replaced.  Turned out motor
mounts needed adjustment.
Regards,
Dieter

 >One minor problem though...the engine
>replacement has resulted in an intermittent rattle apparently due to the
tight
>clearances between the exhaust system and the tow bar. The dealer has
attempted
>to track this one down but because the rattle is not consistent and occurs
only
>when the vehicle is moving, it's difficult to pinpoint the source.