It sounds like it's overboosting, which usually suggests a problem in the vacuum system that controls the VNT mechanism .... the solenoids which control this can and do fail.
Or it could be a leak in the vacuum pipework which is causing erratic boost control, which again would put the engine in limp mode.
Any stored fault codes may be misleading, they tell you the symptom but often don't identify the true cause .... which is why dealers often simply say "new turbo"
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