Just a few days ago, when I start the car up, the engine knocks. Sometimes I you can hear it when it's idling but that doesn't happen very often, it's mainly on start up.
I changed the oil to 5w-30, full synthetic last night and today when I got to work it started knocking on idle. Not loud but I could hear it. When I went to lunch, it knocked on start up but not on idle. I live about 35 miles from where I work.
I'm thinking timing chain is loose.

I know all about the poor performance of the 2.7 but I don't think it's related, at least I'm hoping it isn't.

The engine has 159k miles on it.

Any suggestions?
Thanks.