2002 AUTOMATIC Solara Stalls

I'm relatively new to working on cars and can only work basic maintenance procedures like brake pads, oil changes, windshield wipers (that's pretty much all I can do...), but this is something I've taken quite the interest in. So the reason I'm posting is to mention that my friends 2002 high-mileage, automatic Toyota Solara stalled while he was driving. Upon doing some google searching, I found something about an air control valve. I was just wondering if someone could help me out to help me fix his car. Thanks Reddit!