engine knocking Options

[jcaron9gt4]

well, as the title says, my engine has been knocking recently. It only does it once in a while, not all the time. Mostly only on startups. however, it also does it when i come to a light, or stop sign...etc. Also when i come to a stop, my oil light flickers sometimes and my rpms drop to like 500 then rise to normal. I check my oil all the time and never let it get low. So i have no idea why it comes on, but the knocking is what's really scaring me. Does anyone know what can be checked to figure out the problem. However all this has been leading me to believe that my engine is on its way out.
btw, i posted in here because its turbo'd, someone can move it into the engine forums if need be...any help/advice will be helpful.