I've got a 1991 5.0, with about 104 thousand miles on it. I recently noticed that after I sit at a light for a minute and then start going again, it blows blue smoke out the back. Once I'm moving I dont really see any. Obviously its burning oil. Are my rings worn out? I put a new PCV valve in it but I couldn't get that mesh filter out from underneath it, could that be it? There is also some evidence that my upper to lower intake manifold gasket is leaking, could that be it? Anybody know if theres anything else I should be looking at and how to fix it?