Ok now this is getting insane

New o2 sensor, now the car will idle at 400 RPM and shoot black soot/white smoke out everywhere.

Even when I leaned out the AFC to -40 it did nothing to help.
The Karman Hz are still at 3.

Still think its a vac leak? I'm out of ideas as to where the leak could be...

Edit - its pretty unlikely to detonate to the point of engine damage when you're not on boost, right? As in, should I do a compression check and see if I blew something up? The engine never saw over 2k rpm and never more than 5-10% throttle..

---------------------------------------

Black 98 GST missing her owner and looking for a new one...Inquiries welcome