Idle adjustment on 84 DeVille 4100

A friend has a cream puff 84 Deville with a GM replacement motor. Problem is that idle never goes below 2000 or so. The idle control motor does move the plunger in and out some, but it never calms down. Currently, I took the idle control motor off. So does anyone know how to adj idle, and then reset tps to spec?
Thanks

The base idle is set to about 400 rpms the tps should be .5 v, It is possible the isc is bad and does not retract fully, common problem on the 4100. You cannot run without the isc, any check engine for say code 30?

I havent checked for codes...I dont know how on these Cads. What is code 30? And yes, hte ses light did come on after removing it. My little Auto Xray doesnt speak Cad either. Do I press the hvac buttons to get codes? Thanks for the info Max. Ill advise him to try an idle motor-I wonder where to find one?