Speedo not working and car stalling?

[pj rage]

I was reading quick on another forum about a different car (not sure make or model) that was experiencing what seems like the exact same stalling problem (no mention of speedometer). The person said that it was the IACV (Idle Air Controller Valve) that was the culprit. Does my mustang have one of these and if so how could I go about checking it?

I was also thinking, is it possible that this is a vacuum issue of some sort? I'm going to check quick when I get home, I just haven't had the time since I got home after the problem.