Absotively - I always pull the ground (first) rather than +12. There are some other delightful failure modes as well, such as your big college ring or metal watchband coming between that wrench and ground.
Not sure what the gizmo is called right now, but it mounts on the backside of the DS strut. Hose from it runs over to metal tube on engine. Check that system out. It was the source of wierd idle on our '84. Metal tube had cracked near the rubber hose. Actully found it, trying to fix heater hose leak.