Wouldn’t have thought a coil shock would help it going along or up hill, people often fit them to get better (or different) performance going down. I’ve owned a few Transition Smugglers, one with monarch shock, one with fox shock and not had issues climbing, often ran in trail mode mode for climbing as fully locked out feels pretty crappy for anything off road.
As with anything else, check sag, air pressures, shock setup first. Play around a little with that before spending too much money. Have you checked for tokens (or bands) inside the shock sometimes one more (or less) can help how it feels.