It could absolutely be the manual lever position sensor (neutral safety switch). It is mounted on the drivers side of the transmission. The sensor is pretty easy to install. Some of the older ones require that a new connector be installed with the new sensor. I don't remember which ones. If the connector is different, that would be why. From
Ford the new sensors come with the connector of required most times. To replace the sensor, put the transmission in neutral, unbolt the sensor and pull it straight off. When installing the new sensor there is a line on the sensor when in neutral. Keep the line aligned when bolting it on. (the line is split on the stationary part and the part that rotates). Install a new connector if required and you are good to go. If you had a scan tool you could make sure this sensor was bad before replacing. There could be another issue, but without a scanner to test it with we won't know. The MLP is a good place to start though, it is a common failure. I hope this helps, if so please accept this answer. If you need more assistance, just reply back and I will be glad to help you.