Valve core is probably bad, just take one from a spare wheel. You can remove it with a narrow flatblade screwdriver if you don't have a valve stem tool, just drop it alongside the valve core and turn.

Air shocks themselves are not a good idea for performance or handling. When joined by a common line, when cornering the outside goes down and pushes air to the inside, creating more body roll. Proper wheel/tire size, good springs and gas shocks are much better.