Abstract: A power and deceleration governor for automotive engines according to the present invention, may conveniently take the form of a carburetor power and deceleration system incorporating an intake manifold, vacuum controlled, butterfly type mixture flow control valve, that is disposed downstream of an idle system injection outlet of a carburetor for an automotive engine. The flow control valve is operative to terminate injection of fuel mixture into the intake manifold of the engine during phases of the engine deceleration to allow full flow of idle fuel mixture during idling of the engine and to restrict the flow of fuel mixture during acceleration above a predetermined maximum rate. The system may also incorporate means for metering exhaust gases from the exhaust manifold of the engine to the intake manifold downstream of the flow control valve of the power and deceleration and governor system.