I had my upper intake manifold out of my car to clean the bad carbon deposits. While I had that off, I removed both of my valve covers to replace the gaskets. I cleaned both the valve covers and upper intake manifold with brake cleaner. When I put it all back together and ran my engine the car idled at 1500 RPM. So I rechecked all the vacuum lines and connections and they are all alright. My next suspect would be that the gasket between the upper and lower intake manifold is leaking. What do you think? Also, near the back valve cover it sounds like something is being chewed now. I can't figure out what that is. Any help would be greatly appreciated.