Engine rattling

First check you oil level. Low oil can cause a rattling type noise from the top end of the engine. They do a visual to make sure there isn't a heat shield or something that is rubbing or hitting another part while it's running. If this get's better when hot it could also be an exhaust leak but that could also mean something is expanding in the engine and getting quieter with heat. So many variables here and only a tech who can perform a hands on inspection will be able to know what's happening for sure. Use this link to find a good shop near you. https://repairpal.com/repair-shops Alex