Welcome to Bonneville Club! Some possibilities include: bad battery cables, bad ground bus, bad ground for PCM, bad ground for ICM, bad Crank Position Sensor, bad Powertrain Control Module.
Insulation must be peeled or cut back on cable ends to see corrosion within. A very common problem. Ground bus is under the driver'* door kickplate near the front of the door, PCM ground is by the oil filter, ICM ground on a bolt under the coil packs, CPS under (behind) the crank pulley. Not sure when the PCM moved to the engine compartment, but in my '95 it is behind the passenger side hush panel (beside passenger'* right ankle).