I'll agree that i used to have a vacuum leak. It was a bad brake booster and actually, when i changed it out, is when this started happening. It used to idle down when i bottomed the screws. Once i changed the booster (old one would idle engine down pretty low whenever i'd brake), this occurred.

Yes the choke is open, i let the engine get up to running temp to do this. The only thing i don't do is set the actual idle itself by tach because i don't have one so i just guessed and it sounds about 800-900.