There is provided an injector assembly having two or more oxidizer manifolds and/or two or more fuel manifolds for delivery of liquid propellants to a combustion chamber such that combustion instability is reduced or eliminated during throttling. Delivery of the oxidizer to the oxidizer manifolds is controlled by an oxidizer valve, which may comprise an integral valve. The oxidizer passes from the oxidizer manifolds into the oxidizer element and then into the combustion chamber. The multiple oxidizer manifolds allow the oxidizer to be provided through selective openings of the oxidizer element thus reducing the change in pressure drop across the oxidizer element to thereby reduce or eliminate combustion instability and other problems. Additionally, the injector assembly may also include a lift-off seal or a filler fluid source to fill any temporarily unused oxidizer manifolds with an oxidizer or filler fluid.