S/C BRZ running lean, stalling, surging

[Hikari1]

Hey everyone, hoping I can get some help here.

Been running an Edelbrock supercharger for about 2 years, regular oil changes, build list here:
Edelbrock S/C
Updated Bypass Valve
Tomei Header & Overpipe
HKS dual res Front Pipe
Full Blown Motorsports Oil Cooler
Tuned by Delicious
OEM fuel pump and injectors
OEM spark plugs and coil packs
85,000km

Car handled the track day fine, except for when the belt slipped and sheared off a rib. Swapped to a spare and drove 30min to cottage fine. 2 days later went to drive home and about 15min into the drive I noticed RPMs drop while cruising at about 80km/h in 5th gear. I could hear the belt chirp everytime the AC compressor kick on so I assumed the belt was stretched as it was an old I kept as spare. Seemed to run fine after turning off the AC for the remaining hour home.

Swapped to a brand new belt, car drove fine for about 30min to a meet, when trying to leave the meet the car would start up but then stall when going to idle. I thought it might be out of gas as it was very low and I planned to get more next to the meet before I left. I filled it with 20 litres and it still had an issue stalling at idle on startup. I was able to get it to idle by applying throttle at startup for a couple seconds and it would idle fine after that. Drove it home and AFRs seemed to be okay, thought it was the fuel being low.

Couple days later I drove 30min, car seemed completely fine on highway and city streets, when suddenly, going 60kmh the car started surging wildly, RPMs bouncing up and down and AFRs all over the place. I put the clutch in and the engine stalled immediately. When trying to restart it kept stalling on idle. I managed to get it to keep running by giving gas, it chugged a bit at low speed at first but after a minute it drove 5min to my dad’s place fine.

I've been trying to diagnose the problem but I'm at a loss. The car on cold start will start up although will be running rich, about 12.5-13... I let it idle for about 20min to warm up and was still showing the same on the wideband. I slowly brought the revs up to see if there was any change and the wideband spiked to 17.5 and higher so I let it come back to idle and it remained running lean. Every attempt at starting the car following it being warm resulted in the engine stalling on startup, even when attempting to add throttle.

I can hear the fuel pump priming when I turn the car on, fuel pressures look fine as well. I replaced the PCV valve as there was a slight leak on it, no change. I've swapped with a spare MAF and the issue is still the same. I checked the bypass valve on the Edelbrock, it doesn't stick at all, holds vacuum, and holds pressure. I pulled the passenger spark plugs as they were original with 85,000km on them, 20,000km of that with boost and 5 track days. The tips were very white so I'm replacing with new ones regardless.

I did some data logging for Bill @ Delicious of its behaviour, but I’m at a lost for what it could be at this point.

Logs are at this link if you want to look:
Log 1
Log 2
Log 3

[tomm.brz]

Sorry, logs need to be loaded in datazap.me and then linked here

[Hikari1]

Originally Posted by tomm.brz

Sorry, logs need to be loaded in datazap.me and then linked here

Oops, fixed!

[Hikari1]

Fixed the issue, I replaced the sparkplugs with new OEM ones and also cleaned the MAP sensor. The car has been driving fine since!