Replace mass air flow sensor now car won't run

Hello, it sounds as if maybe these parts were replaced as a guess for something? Your engine's processor may need to relearn the running strategy, but at the same time, perhaps something else was causing the issue that led you to replacing these parts? For example, "lean" running codes are almost never due to part replacement, but often due to vacuum leaks. Has this been checked? Also, are wiring connectors suspect? Did you use original equipment GM parts?