Unable to achieve steady state PSI on Airbrush

Picked up from Amazon "Master Airbrush Cool Runner II Dual Fan Air Compressor Professional Airbrushing System Kit with 3 Airbrushes, Gravity and Siphon Feed" and noticed on G22 airbrush no matter what PSI I use, the steady state PSI drops to 28 psi when the airbrush is on longer than a few seconds. This results in me having a hard time pushing any paint that is not water thin through the airbrush.