I have 2 questions about my 2005 LS V8. Is the Intake Manifold cast or plastic? Is there a pattern of the manifold itself causing leaks or is it reasonable to presume that I can just replace the gaskets? Background: Suddenly started running rough on cool weather startup and showing CEL and P0171 and P0174. Throttle response lags throttle, but gets better when warm. Dealer says that they sprayed carb cleaner near intake and idle came up, implying a leak. I trust them on that. They wanted to sell me an entire intake manifold since they can't get two of the types of gaskets. I found the gasket thread here on LvsC, and have found on-line sources on ebay for each of the gaskets on the ends of the manifold and the eight that couple it to the "tune runner" (that's what the mechanic called the spacers below the manifold and above the block). I was hoping y'all could clue me as to how much risk there is in there being an actual problem with the manifold itself. I have a coworker who has a deep hot rodding and mechanical engineering background and he warned me that there might be issues if the manifold is plastic or could even have issues if it is a cast manifold. I'm a Ford guy through and through, have a '90 Mustang 5.0 Vert and a low, low mileage '96 F150. I work on those vehicles to a limited degree, but typically have the dealer work on my Lincoln.