[quadracer12]

Some fox shocks literally just work on air, while most normal shocks have a certain weight oil with nitrogen in a bladder in the reservoir or emulsified in the oil with no reservoir. The nitrogen stays much more consistent when pressurized and when it is heated and cooled than air does, this is the reason to use nitrogen. Air expands easily and can damage your seals. The air shocks use the air as the spring (when it gets compressed the pressure builds up and pushes back).

It sounds like that shock really needs a rebuild! I would just send it to a shop and they will have nitrogen to refill the shock and replace/rebuild the valves as long as the cylinder walls are still in good shape.