Spark plugs: 8
The reason why your 1991 Ford Ranger 2.3L has 8 spark plugs but only 2 fuel injectors is because it has a distributorless ignition system (DIS). In a DIS system, each spark plug has its own ignition coil, which means that there is no need for a distributor to distribute the spark to each cylinder. As a result, there are two fuel injectors (one for each bank of cylinders) and 8 spark plugs in your engine.