Previa Intake Manifold Leak

Sounds like you're on the right track with the intake manifold. The symptoms, especially with the stalling and rough running, point towards a vacuum leak. Have you checked the manifold pressure readings? If they're fluctuating wildly or consistently lower than expected, it strengthens the case for a leak. Also, have you ruled out a faulty manifold sensor? That could also trigger similar issues and store error codes.

I haven't swapped the sensor yet, but I thought a faulty sensor would throw its own specific code? The code I'm seeing seems more generic, hinting at a mixture/combustion issue. If the manifold's leaking as you suggest, would I expect to see misfires logged too? I noticed the values are unexpectedly low. What readings exactly should I be looking for from the manifold sensor?

You're right, a faulty sensor often throws a dedicated code, but not always. A leak can definitely cause misfires and a generic combustion error. As for the manifold sensor readings, you'd need the specific values for your engine, but generally, you should see a consistent pressure reading at idle (relative to altitude) and a smooth increase in pressure as you accelerate. If it's jagged or lower than expected, especially at higher RPM, it suggests a leak. Honestly, with all those symptoms, and especially if you see scorching, it might be best to get it pressure-tested by a workshop. Could save you a headache.

Appreciate the insights! Turns out you nailed it. Took it to the shop, and yup, intake manifold was leaking like a sieve due to scorching. New manifold and gaskets set me back 1180€, but the Previa's running smooth as butter now. Thanks again for pointing me in the right direction; would have been chasing ghosts otherwise!