If one of the cylinder fuel injectors were to stop spraying for any reason,
I believe the OBD-I system with its single Oxygen Sensor, would falsely calculate “too lean air/fuel”
and lengthen the “on time” of injector pulses,
which would eventually have the other cylinders become rich.

Could be bad wire in harness to injector,
bad injector coil,
plugged up catch screen at top of injector,
etc

There have been multiple reports by past Ram owners that the inner liner of the fuel hose starts breaking up into pieces that then plug injector catch screens.

On OBD-II Rams the PCM can compare the pre-catalytic Oxygen Sensor to the post-cat Oxygen sensor and give a more informed trouble code