well since it drops to 4-500 rpms then jumps up to 800 like you are saying it seems the idle control is alright, the idle doesnt seem like its that bad if it just drops once and then jumps to 800 and stays steady, the bogging is what bothers you more right? when it bogs, is it ALWAYS at certain rpms or randomly, and does it feel like the engine is just dead for a second or describe it more how it bogs.... sounds like either a spark/fuel prob, or loose wires going to the ignition module, but for it to be loose wires to the ignition module it would have to feel like the car, DIES for a second, and it would be more random.