I have the opposite effect in my 94 rt, it idles all over the place!
If its single point injection then you wont be able to adjust the idle control screw or this will just mess it up even more (or so Ive been told by experts). If you adjust the screw, then the ecu doesnt know what you are telling it and so it messes up the air and fuel flow!
So what you have to do is go to a specialist fault diagnosis place or a rolling road place that tunes engines and ask them to get it running smoothly! Mine still isnt fixed, but Im probably gonna take it to a rolling road and see if they can sort it!
Danny