Corolla Boost Pressure Problem

That sounds like a real headache. The whistling and hissing, combined with the power loss, does point towards a boost pressure problem. Have you checked for any obvious leaks in the hoses or intercooler? Could be something simple like a cracked hose. When was the last time you looked at your boost control solenoid?

Thanks for the quick reply. I did give the hoses a quick once-over, but nothing jumped out at me. I confess the boost control solenoid is not something I know a ton about or specifically checked yet. Where is that usually located on the Corolla? Is there a way to test it myself, or am I better off just taking it to a mechanic at this point?

Okay, makes sense. Honestly, with all those symptoms stacking up, especially the stalling, it's a bit beyond a simple hose check. Plus, boost control solenoids can be tricky to diagnose without proper equipment. The wastegate valve is a common culprit in these cases, and when it fails, it will cause all the symptoms you describe. I would advise you to take it to a trusted workshop and have them perform a full system diagnosis. I’m fairly certain that this is related to a faulty wastegate.

You were spot on. Took it to the shop, and they confirmed it was a defect in the wastegate valve, just like you said. They quoted me 860€ for the repair, which stings, but at least I know what's wrong now. Thanks a million for your help. I really appreciate it.