3400

Every once in awhile my engine will rev up and down a few times when I start the engine. I've read it's a vacuum leak. Is that all it could be? Why doesn't it do it every time? Where are the common places it could be leaking from?

Recently I changed my oil in my 2000 Alero 3.4L and the oil had some milkshake color (light colored) in it. I did some researching and the majority consensus on the internet was the intake manifold gasket. I replaced it and in the process noticed the inside of the valve covers were plastered...