2003 Cavalier auto 116K miles - Car is sputtering and stalling at stoplights with a/c on. What can I check? thanks!
The first thing to check is whether you are up to date with ALL of the required maintenance on this car.
If everything is OK in the scheduled maintenance department, then you should check the Idle Air Control (IAC). Simply cleaning the IAC could resolve the problem.
Check engine light on?
VDC - this will sound really newbie-ish but I looked forever for that valve and cannot find it. I read it is on the throttle body - is the tb where the air comes in? A pic would be awesome. No check engine light.
Yes, the TB is where the air comes in - the downstream side of the big black snorkel at the opposite end from the air filter. And the IAC is mounted there somewhere. Go to any auto parts web site & search for an IAC to get a picture of it. I think that on a Cav all you’ll really see of it is the electrical connector. While you’re at it clean the TB itself.
what gets dirty, the plastic cylinder portion or the metal cylinder portion?
Remove it from the TB & clean the whole thing. Also clean out where it mounts and any passages where it mounts. The part that inserts into the TB is likely something like a plunger. The valve is a little electric motor that pushes that plunger in & out to control the amount of air coming into the engine at idle.
You never did say anything about things like plugs & wires, air/fuel filters. The IAC is only one possible problem - and even then cleaning it might not be enough.