My 2000 Van conversion with a 5.2L. sometimes acts like it has no PCM. I get a "no bus" in the odometer; check engine light; no fuel gage indication; no spark; but the engine will turn over. I've taken the three wire harness' off the PCM and inspected the plugs and pins. Not defects were noted. My OBD reader will not communicate with the PCM when it starts malfunctioning.

 

Yes, all of those symptoms point towards the PCM being bad.