Peugeot 408 Stalling

Sounds familiar. I've got a 408 too. I had similar symptoms a while back: check engine light, rough idling, and occasional stalls. It felt like driving a bucking bronco! Have you tried cleaning the throttle body? That helped a bit temporarily for me.

Cleaning the throttle body did cross my mind, but I'm thinking the root cause lies deeper within the IAC valve itself. Did you eventually pinpoint the IAC valve as the culprit, or was something else causing your issues?

Cleaning helped for a day or two but the problem came back quickly. I eventually took it to a workshop. The intake was indeed heavily contaminated, gumming up the IAC valve. They replaced the valve and cleaned everything, costing around 425€. It was worth every penny!

Thanks for confirming my suspicions! It seems I'm facing the same contaminated IAC valve issue. I'll schedule a workshop visit. Hopefully, that'll fix this stalling issue. I appreciate the insight!