97 Olds Achieva 3.1

Vehicle is leaking anti freeze after i shut it off. was looked at and was told that the head gasket is the problem, but there isnt any signs of it in the oil. There isnt any pressure in the coolant lines at all, and after we ran it for a while it dosent seem to be leaking anymore. is there any tests we can do to determine if it is the headgasket (without pressure testing) or if it is the waterpump?

sounds like water pump. Look for antifreeze stains on underside of hood etc where antifreeze on the belt will have thrown off. If you feel the underside of the water pump (motor off!) you will probably notice antifreeze there. There is a bleed hole on the underside. The leak when parked/intermitant leak is typical of water pump.