Sounds like a huge vacuum leak somewhere to have all 8 glowing. Cover the primaries and it still runs = sucking air from somewhere.

If you back the idle speed screw all the way out and it still runs at a normal RPM, something is hung up or leaking.

Ignition timing (Al provided a no cost suggestion, crank in more timing and see if it goes away) is the typical suspect.

Power valve should not even be in play here, unless there is something wrong with the gaskets/blocks used allowing circuits to cross over (rare).