Rough idle... only when warm.

Details man! power brakes? Slant 6 or a hemi? Somewhere in between?
power brakes my have a booster leaking vacuum.
Had a dirty carb, would run not bad until it warmed up,choke would come off and it would get rough. Pulled carb and cleaned it. Solved!
Plugs burning clean?
What do you have for a carb?