update..... So after a month and testing alot of parts on the slingshot way to much to list. The slingshot is back up and running. The part that was causing the stalling issue was the Clutch switch. KPS had tested the switch but it always came back good. That led them to test other items while working with Polaris. After many weeks of frustration and changing out many different parts the problem was the clutch switch.
It was hard for the shop to diagnose because it would only do it every so often. Even while hooked up to ECU diagnostic test it would read good.