The manifold leak is contributing to the code. The computer is reading flow and exhaust temp out of spec. The o2 sensor contains two small wires that arc electricity, as the wires got hotter, the move further apart and reduce the electrical load accordingly, when cooler, they move closer together and increase load. The 'puter is essentially reading voltage skews outside of normal operating range.
2013 Ecoboost Black on Black FX2 SCREW - Stainless Works chambered exhaust, Airaid Intake, SCT X3, Aeroforectech gauge.
2007 Black on Black SCAB sold 14 Sept 13
1996 Thunderbird LX 14.17@98mph sold 13 Oct 12