I have the sniper on my 84 and use the fuse terminal (crank/run). As SquareRoot said make sure and test that it has 12 volts both during crank and run.
Went on a 500 mile trip today to deliver a mini truck. Ran great no issues with the sniper. Happy so far, cold start idle is the only thing to fine tune.
Added some side boards today (I like to be a little different). That way if there’s a matching pickup in the parking lot I know which one is mine. That has never happened but you never know.