2.7s are a sh*t design. If it is sludged real bad, you may have low oil pressure that can't drive the timing chain tensioner out with enough force to keep the chains from slapping. It would be worse at idle, and could be from a blocked oil pump pickup or a worn out pump. If you see the oil light flickering at idle, that is a good sign that that's what's going on. I went through this on my ex-wife's old Intrepid.
My advice, get rid of it ASAP.
My advice, get rid of it ASAP.