can't get idle lower than 1000

So what you are saying is you can't richen the idle mixture enough correct?

This could be due to a couple factors. Either the carb isn't running off the idle circuit or the idle circuit won't go rich enough.

First take the carb off and turn it upside down (drain the gas first) look at the primary throttle plates from the the rear of the carb. There is a small slot in the throttle bores, this is your idle circuit. If the throttle blades are open past the top of the slot you are not running on the idle circuit. You can crack the secondaries open a little more to compensate so you can close the primary throttle blades in order to bring the idle circuit alive.

If this doesn't work the next step is to reduce the idle air bleed orifice size. Most Holleys come with like a .070 hole or something. You can put a dab of Devcon F epoxy on the air bleed and redrill it to .040 or just get new air bleeds. These are the outboard air bleed holes in the carb air inlet area. Do just the fronts first. You probably won't need to do the rears but maybe. If none of this works the last resort would be to drill the primary throttle plates to get more air into the engine while keeping the throttle blades closed enough to activate the idle circuit. But that will be another post.