I have a 78 Firebird with the 400/4 barrel. The engine is stock, as it came from the factory. I've tuned the car up (plugs, wires, cap, rotor; carb was rebuilt a while back). Normally, the car runs quite well. However, if I drive it, let it sit for an hour or two and let the engine cool off, and then start it, it idles poorly. Then, when I go to accelerate, it runs rough, misfires, smokes, etc. for maybe two miles of driving until it fully warms up again. Then after that, it's fine again.
I know this is engine temperature related, and I'm thinking it's some vacuum controlled emissions component that is not working right, or something like that.
Is there anyone on the list who is familiar with these cars or related vehicles from this time period, who might have an idea of what I should look at as possible causes of this problem?
Thanks.