Tracking Issues Google Analytics / Shopify

We are having some tracking issues, probably due to double implementation of diverse tags, which we need to clean up. We believe that due to these multiple tracking tags we are missing out on data in Google Analytics such as avg. time on page (shows 0:00 often), high Bounce Rate (often close to 100%). This hypothesis has been confirmed as a possible problem by both Google and Shopify so we need someone to clean up our tags on Shopify's code to have everything set up correctly. Bear in mind that we're tracking conversions through Enhanced Ecommerce, which needs to remain intact.

Job Requisites:
- Someone confident with Marketing Tags (google ads/google analytics)
- Someone with coding experience on Shopify
- Someone with codice experience related to Enhanced Ecommerce (already set up, just needs to stay intact).