my 2000 superduty 5.4 engine rattles at startup. quiets after about 1 minute. could it be worn out l...

I wouldn't be able to tell unless I heard it. This is a good site to go to try and diagnose a noise, smell, feel, and so on. Best of luck.
http://www.autozone.com/servlet/UiBroker?UseCase=S001&UserAction=viewSimpleDiagTypeInfo