I've adjusted my edelbrock carb so many times and some mornings its goo but others the thing idles at 2500 rpms until i put into gear. If i choke it it does this but if i dont it wont start. Often in the freezing temperatures (0 degrees to 32 degrees) it goes really high and then tapers off as the motor gets warmer. What in tarnation can i do to get the idle lower. Ive adjusted the screws to the point that the truck dies and the next day its back up high again.

 

could be that your floater is stuck inside the carb.

 

I don't know if I missed it somewhere, but what year, and engine. If it is an 86 then there is a adjustable screw behind the IAC. Also check if your Coolant Temperature Sensor is working. That has a great deal to do with idle on these trucks.

 

Check gaskets for vacuum leaks

 

Can you post a picture of the carb?

 

The first thing that runs through my mind is a vacuum leak....something else that you can do is take some WD-40 or brake parts cleaner what ever you have on hand..spray it around the base of the carb you put on,and see if it gets even higher... if it does it's sucking air around the base of the card...if it doesent,do the same thing around the intake and see if it might be sucking air around the intake...it's a good possibility... good luck,what ever you do..keep us informed.....jeff