In 1985, Saab began using the new Bosch LH fuel injection system, and Volvo and other carmakers followed suit. The system worked such that incoming air passed through an airflow meter that sent a signal to the engine ECU telling it how much air was going into the engine. The coolant temp sensor then told the ECU how cold or warm the engine was, and it opened and closed the injectors when needed.
It may be possible to restore proper brake and steering operation by flushing the system. After cleaning, if the filter and fluid show obvious signs of hose contamination, all hoses must be replaced and both fluid and the in-line filter changed again.