2001 Dodge Ram 1500 P1687 Code: No Bus Error, Intermittent Starting and Misfiring Issues

I own a 2001 Dodge Ram 1500 4x4 with a 5.2L engine that is experiencing intermittent starting problems. The truck displays 'no bus' on the odometer when attempting to start, and I've retrieved fault code P1687 from the onboard diagnostic system. Recently, during these incidents, the engine would crank but appear to fire only on one or two cylinders before eventually starting successfully. Once running, if I rev the engine to full throttle (in neutral with no load), it misfires and backfires. However, when RPMs are increased gradually, the engine runs normally. Additionally, I've noticed that 'no bus' occurs occasionally while driving—when this happens, all gauges drop to zero even though the engine continues running. This issue seems to be intermittent but recurring. I'm seeking advice on where to begin troubleshooting, especially given the P1687 code and its association with the metering oil pump stepping motor circuit in this specific model.