upon starting car it makes a rumbling noise and then goes away when driving

Hello, A rough idle could be spark plugs and wires, but there are a host of other things that could be causing the issue. You may have a clogged exhaust gas recirculation valve (EGR) or idle air control valve (IACV), a vacuum leak that closes as the engine warms up, etc.. Before spending on new plugs and wires, have it diagnosed. It will likely prevent you from needlessly buying parts.