1995 Aurora

Hello, I have a 1995 Aurora. We have just replaced the idle speed control motor. It is still doing the same thing: When you turn the key (but do not start engine) you can hear it clicking, and feel it on the gas pedle also. When driving and coming to a stoplite, you can feel it tapping on the gas pedle. When you turn off the vehicle, it clicks for about a minute. Does it need to be adjusted in some sort of way, or could something else be causing this. I do have a check engine lite and a diagnostic code of 56 (which I think has something to do with the TSS in my transmission)

Thanks
Cheryl