Idle went nuts.
Well - here are the results in pictures:
1) you can see the damage to pistons #1 and 3 - there are scraps of the washer in #1 and the entire nut in #3. The scraps in #3 are bits of spark plug. I found the bolt, complete and undamaged in the intake behind #4
2) cylinder #1
3) cylinder #3
4) plug from #1
5) #1 chamber
6) #3 chamber
Is there hope or am I shopping for a new engine?