Custom Script for Importing products into Magento 3.1.1

I have a Magento E-commerce Cart Installed. I need to upload my correctly formatted csv list with pictures. The list contains 22,000 products. I used to use the product import into magento until it started freezing after so many products. I need a custom script created, to import my products and be able to use the same script to make updates. This needs to work with Magento 3.1.1.