Welcome to AF !!
What engine and how many miles on your Alero ?
You'll need to get the the car scanned to see why the check engine light is on. Once you have the trouble code its a lot easier to narrow your troubles down.
Typicaly when you're experiancing stalling, thier are several things that might be the cause;
The Idle air control vavle- IAC
Clogged fuel filter(and or contaminated fuel)
Something bad in the ignition system wires or components(coils/ignition control module-ICM)
Bad plugs/wires(v6), or a bad vacum leak.
Id start by getting the code then looking for vacum leaks. Thier should be a diagram under the hood for the vacum lines.
Its quiet possible you had a misfire and popped off a hose somewhere.
Hope that helps.