N55 missing on idle and pulling +30 fuel trims

[jce929]

I’ll try to make this an easy read. 2012 135i tuned on MHD stage 2+ (mods listed at the end). Has had issues the past few months with surging and dying, particularly in lines of vehicles, so I just attributed it to intaking the exhaust fumes. Yesterday it started having a random miss, and pulled the P0170 code for running too lean. Today I had time to go run some checks. I made sure the entire intake system was tightened up, checked the maf, and bled the crankcase. My fuel trims were all over the place. As of now, it sits at idle with the occasional miss, and both fuel trims are around +30. So obviously my issue is too much air, or too little fuel. It started to snow right before I was about to pull coils and plugs to see if that told me anything, so I took a pause, but if all coils and plugs are perfectly fine, then I’m at a loss. I’d assume injectors would be the final thing to check but I’m unsure on how to check individual injectors and it didn’t throw any misfire codes. Any help would be very appreciated.

Engine/Exhaust/Drivetrain:
- Injen Cold Air Intake
- BMS Oil Catch Can
- BMS Charge Pipe
- Custom Mid Pipe
- Custom 4 Inch Axleback
- CTS Catless Downpipe
- 7inch Intercooler
- ARM 3inch Intercooler Piping
- GFB Diverter Valve
- Extended Intake Manifold Studs
- VTT Inlet Pipe
- Dinan Coil Packs: 20k miles ago, plugs 2k ago
- Aluminum PS Cap & OFH Cap
- Aluminum VC