If it only rattles for about a second on a cold start then it could be the tensioner building up pressure. This is considered normal especially with higher mileage. You could check the cam deviation to make sure it is with specification using a Durametric or equivalent scan tool.
Hi RobT987..I have checked all that, and so far Iam on the edge of being out of spec, but No CEL yet,..and that's the only Tensioner I have not replaced,. Thanks Frank