Gauge sensor and ECU temp sensor are different things. Can't be -36 on gauge sensor or it would not move at all. ECU temp sensor reading -36 with warm engine would certainly give you problems as would fuel temp sensor reading that low. Number four injector signals point of injection to ECU. ECU adjust timing solenoid in pump from that information. Any fault with number four injector should put engine check lamp on even if it just flashes it momentarily. But it is not beyond the bounds of possibility that the throttle potentiometer is faulty.
