So I CEL coded P0300, the engine was juttering every so often. Thanks to your advice swapping the packs worked. Well- 2 4 and 6 all swapped, took longer to CEL but the engine was still jumping a bit. 1 and 3 swapped cause I couldn't get to 5 easily. The joys of a transverse V 6. Started it up and HOLY JEEZUS HIGH REVVING BATMAN apparently leaving the EGR hose off causes a 3k idle. That plus the res delete and new flowmaster scared the crap out of me. Killed the engine and reattached. Idled for a while, warmed up as normal. no CEL or rough idle. Yay.
Ok let's turn my car around so I can rotate the cockeyed projector. Brake. Brake. BRAKE Stop! Took full force on my brake pedal to stop. Wtf Batman? Forgot to reconnect the egr hose that was over coil pack #6. So turns out my brakes were vacuum operated - who woulda known.
So this concludes today's lesson on the importance and extent of your vacuum system.