can't get idle lower than 1000

We really should start by knowing just what all this combo is specifically. Cam duration @ .050, type of intake, carb make and size, what booster type is the carb, jetting, power valve, are the throttle plates drilled, vacuum or mechanical, headers or manifolds, stick or automatic. Is this out of gear or just in gear, is this a fresh build or was it a running engine and this just started or was something recently changed, what distributor, vacuum or just mechanical advance, locked distributor, what is your base timing, what is the total timing? There are so many possibilities that without basic information we are just making wild *** guesses.