[MARZBX157]

From what Your saying, it sounds to me like the Transmmision Range Sensor could be bad. There are a lot of threads on this subject. it's the sensor that sits on top of the tranny, under the intake air filter box. You can try uplugging the connector while the engine is running and drive it around the block and see if the tranny shifts through all gears (might shift harsh). If it does, then you need to change the it. Do a search in this forum under Transmission Range Sensor or also known as a Neutral Safety Switch.