Gen 3 dies, I get check engine and triangle,

No wonder you have all those codes. Those hoses being disconnected are making the MAF report lean conditions. It screws up the whole fuel management system. Put them (hoses) back on, clear the codes and see if you can put it through a recommended drive cycle.

 

This is a couple-year-old thread I found while searching, pardon the bump but I just wanted it to at least have one mention of the right answer. And here's further information with the solution: Engine behaving strangely and popping hoses off intake manifold | PriusChat

 

Interesting! Detonation in the intake, I would imagine. Perhaps an intake valve hanging up, or the infamous EGR plug up.