I found the problem to a start-up rattle I've had since new on my 05 GT. 60000 miles on car now. A tsb https://www.stangnet.com/images/stor...s/06-19-08.pdf claimed it could be the cam phasers. I felt it was more like a sticky lash adjuster so I removed all the lash adjusters and cam followers and checked them. All were good. I then removed the cam phasers and checked them for bent broken pins. They were good. So off came the front engine cover. After checking the chains and guides I ordered new cam chain tensioners and installed them even though they looked good. I've been driving for 3 weeks now without even one start-up rattle incident. I cut open the old tensioners and think the problem may have been the check ball valves leaking back.

Between fixing my squeaky clutch pedal in a previous post and this start-up rattle it feels like I'm driving a new car again. Sometime the smallest issues can be the most annoying.

 

Thanks for sharing. 60k is a little soon for one of those to go out.

 

Thanks, that's a good tip brother. I'm glad your's is better now.