[HO455]

I have the same carb as you do. First I suggest you download the manual from Edlebrock's website and familiarize yourself with the choke components. The choke coil on the passenger side of the carburetor operates the fast idle parts on the drivers side of the carburetor. You may be missing a piece or things may just be cruded up. Once you are satisfied the linkage works as designed set it to the specifications in the manual for a base line. Check to see that you have 12 volts at the choke coil and that the ground wire on the choke coil is hooked to a good ground.
Then drive the truck and see how it works. It is likely you may have to make some adjustments. Don't get frustrated if adjusting it to perfection takes a half down or more tries. When setting up a choke I will make an adjustment before I leave work, then I drive home and back to work, giving me two cold starts to compare and decide what the next adjustment will be if I am not satisfied.
The idle may be too high or low for the average temperature of your cold start.
The choke plate may need to be open or closed a little bit more to get the engine to run without stumbling on moderate acceleration.
Ideally you want the fast idle screw to be sitting in middle of the fast idle cam with the temperature in the 45-55 degrees range. But this not a hard fast rule just something I have found to work living in Portland. Another thing I have found is that the Edlebrock electric choke coils take too long to get up to temperature. At least for my taste.
I hope this helps.