the engine is not missfiring at all .so theres no problem with compression.The engine souds like a diesel motor.It makes a very low rattle at idle and tapping sound at around 1200 rpm.

 

i got the same thing it seems... only get it once the oil warms up

wish i knew what it really was, as it seems the answers are mixed

 

The 2.8L oil pick up tube won't get clogged, so no need to worry about that. If you have already replaced the tensioner and given it the seafoam treatment, it might be a sticking lifter bucket. Does it only come from one side of the engine or does it sound like both? When was the last time you had the timing belt/water pump changed?

 

THE noise is coming from passenger side valve cover .It makes arattling sound at idle and whenyou rev motor between 1200 and 1500 rpm it makes tapping sound like a bad lifter.i have replaced all intake lifter tappets (3x3) i also replaced chain tensioner, and it still makes noise.....it goes away when you rev motor past 1500 ..I even removed oil pan and inspected pump pick uf tube & screen...replced oil and filter . still makes noise.....