89 Silverado 3500 454 idol sticks

Hello Forum my name is Jeff and I have a problem with my 89 Dually tow vehicle.
I have basically replaced everything now and have a problem with the idol. When I come up to a stop sign or traffic light the idol is rather high, I have to tap the gas pedal and then the idol goes down.
So far I replaced:
Throttle body
Fuel injectors
Gasket
Throttle cable
Sensors
Throttle Thingy on the passenger side with a plunger on it (sorry cant remember the name)
EGR
I am completely stumped at this point and need help

Disconnect the linkage from the tb, see if raising the idle by hand and releasing it causes the same issue, post back.

Maxwedge I can not duplicate the problem in the driveway it only happens when I am driving and coming up to a stop light or sign. But I will try it again tomorrow because I have never tried this without the throttle cable. There is a Ton of tension on the throttle cable.
Thanks so much for the quick reply !!!

Thought I would post this quick video for any one interested. This is a project I have been working on for the last 15 years. If you could convert thrust to Horse Power this is about 5,000 HP.
The motor burns 200 pounds of Nitrous Oxide in 20 seconds
http://www.youtube.com/watch?v=uqLmnA-BKwg