Most likely you have an EGR port clogged with carbon build-up, common on these 3.1L and 3.4L engines. Remove the throttle cable bracket and look down the PCV tube hold on top of the intake. Also check the PCV operation and ensure its not sucking oil out of the valve cover. If it is, oil will fall on top of the EGR port. May be easier to remove throttle body to clean carbon build up.