For the late 90s Rams – That’s an EFI system that controls spark (EZ doesn’t), probably has a PWM fuel pump and returnless fuel system, and the ECM controls the alternator. As XCraig mentioned, the battery acts as a voltage spike buffer, so I can see how a bad battery might sometimes cause an idling issue, as the ECM is trying to control fuelpump and injector control, Vreg, Idle Air Control, and spark timing on noisy voltage. That’s a more complicated animal than EZ.
