Hey I'm new to this all. So apologies in advance if I forget to mention anything that can help.
(Long tubed headers, custom tune from previous owners, cold air intake, cat delete)

I have a 2013 Mustang GT and recently it has started to have an intermittent misfire. Air/fuel ratio drops to 10 during misfire. Codes originally pulled missing on cylinder 2 but swapped over to cylinder 1. Had codes for O2 sensors (b1s1 and b2s1 cat delete so no s2's). Replaced both O2 sensors and plugs, tested MAF; still good. Checked harness out for injectors and O2, no issue there. Ignition coils in good shape and didnt change misfire when swapping one over from cylinder 2. injectors changed 30kish miles ago. checked for vacuum leaks, none found.

Looking at data stream when car is running, Short term fuel trim on bank 1 will jump to 68% and bank 2 will drop to -28% at idle. When misfire is gone, both fuel trims sit around 4%-7% at idle Thinking my issue is coming from a fueling issue. Any pointers or leads would be appreciated.

 

Swapped injectors around, fuel trim issue swapped to bank 2 instead of 1. Replaced all injectors since issue pointed towards faulty injector. Issue still remains in bank 2 now.

 

Well just to help anyone else out who comes across this issue, took my car into a shop I trust and had them dig around. Turns out the intake valves on cylinder 1, 2, and 8 are toast. Gonna have the whole engine, top end and bottom, rebuilt just since its been beat to hell and back.

 

Thanks for taking the time to post your experience and what the solution was. Sorry to hear it's not going to be cheap but, it helps the next person have a reference for one possible solution.