My friend had a 3rd generation Mustang with a 4 cylinder engine. That POS ran almost as well as a diesel as it did with the ignition turned on.
Ford circulated exhaust gas around the base of the carb when the engine was cold but the solenoid for this seldom worked very long...in short the system was a mechanics nightmare.
Anyone that has never experienced owning one of these old pollution control engines can never appreciate the benefits of fuel injection.