I have a 1974 f-250 camper special with a 390 and i just can't figure out why the truck is running and idling great when cold but when it gets up to temp, the truck idles rough and sputters from a stop up until about 20mph. There is no problem once i get up to speed. The symptoms seem to be almost like having a bad egr valve but there is no egr on this engine. If anyone can help that would be greatly appreciated!

 

If the carburetor has never been rebuilt/updated for unleaded fuel, the float needle and seat may have swelled and is causing it to run with a lower than normal float level. When cold the choke is compensating by adding addl fuel. Should have a 4bbl carb and could need an accelerator pump diaphram too.
I don't recall if your carb has externally adjustable float level adjustment.

 

It has a fairly new edelbrock 1406 I installed

 

Sometimes,,,,,, if the idle mixture screws are set too lean it will cause a rough idle and stumble on acceleration. Some others had an adjustable accelerator pump stroke .Since the idle is affected I would consider opening the idle mixture screws maybe 1/4 to 1/2 turn each and see if that helps correct the problem.