The intake runners are part of the intake manifold. It's typically a dealer-only item because it doesn't fail unless it is cracked in a crash. Vacuum leaks in the gaskets are fairly common, (extremely common on GM trucks), but you don't have to replace the entire manifold, just the gaskets. Ask your mechanic why the entire assembly needs to be replaced. If it is made of plastic it might have warped. That could be a common problem with Ford only and would explain why it is on back order. That means they can't build 'em fast enough to meet demand.
A leak in the gasket, whether it be due to a defective gasket or a warped manifold would let extra air get into the engine and would result in the lean condition fault code.
Monday, February 14th, 2011 AT 5:20 AM