not getting switching signal at cop coil conn on cyls 456&8 is it a bad pcm?

'IF' a proper SPARK TEST has proven those 4 coils are indeed not firing - suspect wiring harness damage to the coils - even though you stated there is power at the connectors .. ECM is least likely suspect - but is a possibility. Closely inspect wiring harness for possible small rodent damage (mice love to gnaw on wires)