I am at a point where I need to replace the valve cover gaskets. My gaskets are leaking small amounts of oil on the exhaust manifold so the smell of burning oil gets annoying. I see the passenger one is easy whereas the drivers side is buried under the intake. I assume the air intake system on the top has to be removed for the drivers side valve cover to come off? If so do I need to replace the air intake gasket? It seems like there is one. Approximately how long of a job is this?