How can I lower the idle speed?

[DamnedButDetermined]

My air conditioning is broken, so my engine should be idling at 7-800rpms. Mine on the other hand is idling SMOOTHLY (i only include the word smoothly b/c there are many threads already about irregular idle [going from 400-900-500-1500-stall, and stuff like that]) at 1000rpm. I took off the air intake piping and shot some carb/choke cleaner into the throttle body to clean out the built up gunk hoping that the butterfly valve would make a better seal and lower the revs. That didn't work! (it does look nice and clean though) I then looked at were the throttle cable connects to the throttle body, and there is a tiny adjuster screw with a nut on it, where if you turn it to the right (after loosening the nut of course) the throttle is opened slightly and revs increase. So i turned it to the left but it didn't lower the revs any. I then checked to see if there were any other adjusters or places ( including the throttle cable) that would keep the butterfly valve from closing any more, but there isn't.

So now to my question...
How can i lower the idle speed?

I have reset my computer before and noticed the screw you turn has a sticker around it that says Idle Speed control. But when you reset the ecu you turn it all the way to the clockwise, start the car, then turn it all the way counter clockwise, meaning that it is at the lowest Idle Speed. Is there anything i can do with that adjuster screw that will lower the speed?

I have also heard that there is an Idle Control Valve at the back of the intake manifold. I am 99% sure i have found this control valve but i didn't see any adjustments that i could make. Is there anything i can do with the Idle Control Valve?

I am planning on completely removing the air conditioning in the future, and will be gutting out my water pump and replacing it with an electric one. These two mods will elimitate a lot of resistance on the engine and will in turn make it idle even higher, so i don't want to have an already high idle before i do this. It will sound quite retarded if i am at a stop light and the engine is at 1600 rpms!

Any and all suggestions are appreciated, and please give me alot of them!

thanks,
-DbD-

EDIT: Damn it I always forget to tell you it is a 1990 fastback