Horrible Idle after warming up

[AzCountryman]

Want to say this topic has come up before but here it is.

Start up the truck in the morning and sounds healthy and runs great. After it has warmed up a bit it seems like it doesnt idle well at stop lights....Always end up putting it in N and it idles better. also once its warmed up and I stop at the store or something and fire it back up it hates idleing. Have to keep foot on brake and gas to keep it going until I start driving forward again.

Any thoughts?

327 with Edelbrock performer carb (Carb is 8 years old now).