I have a 1989 SC with 245,000 miles and i have devloped an idle problem. Ive noticed a few things actually. I have a little mix of yellow fluid in my oil. I have also noticed all my cylinders are running lean because of unburned gas on the spark plugs. The main question i have is that when i rev the engine no matter how high i can only obtain 5 pounds of boost. My vacuum does not read more than 21 psi though. Im leaning towards an intake gasket. Theres also a little yellow fluid coming from around IC tubes where the connect into the intake manifold. Rpm idles at 500 and sometimes drops to even 200. Any suggestions?