new 5.0 engine error codes help needed

Aside from the torque converter fiasco, I also have a new engine with a big high/low rpm hunting problem.

I've got a Snap on engine code reader that gives KOEO codes of

173 EGO not switching 327 EGR signal low 328 EGR voltage below closed limit 334 " " Above " "

Any mechanics know what may cause this combination?

Thanks

Dirk