Woohoo, I has the Pulsar back. The problems:
Throttle was adjusted completely shut. No idea who on earth did that. This was the cause of the car trying to stall/stalling while backing off throttle and the cause of the rough idle.
Tune was using the wrong base image file - from an N14. This was causing the overfueling. It now makes 13fwkw more on the same boost - 196.2fwkw, shitloads more torque (617nm according to the dyno lol), the turbo spools much earlier and it makes much more power through the midrange. The hesitation at 4,500rpm is gone. It's quite insane to drive.
Hot start enrichment had too much fuel. This was the cause of the car stalling every time it was started warm.
This tune was on 16PSI, previous tune on 17PSI. More power with less boost
This will go in down the track when I have an O2 sensor (daughterboard with O2 sensor tune):