Alright so I went out last weekend and ran some 110 octane and a 225 shot truck ran fine everything was good until I filled it back up with 93 octane now I'm getting a p0171 lean bank 1 and it's breaking up really bad things I have checked/replaced

- new plug wires
-checked plugs br7ef's, bank 2 looked good, bank 1 was very black and rich.
-cleaned Maf
-new manifold gaskets
- not sure where to go next going to check fuel pressure and o2s in the morning any suggestions?

 

See if o2 sensor is switching.. I have had some randomly stop and they will command rich if so. Po171 is lean bank 1. O2 sensors just read oxygen and the upstream should always float around.(switching) they do this way faster than you could see like 27times a sec or more. If all looks well there check for intake leaks.. And throw a fresh set of plugs in too.. And check for exhaust leaks on before the o2 that can falsely comman rich too.

Hope this helps.. Feel free to pm if needed if you have ?'s

 

I tried to watch on my scan tool I forgot to mention my LTFT1 is at 25% and doesn't change the STFT1 stays at 0 when it's breaking up and shuddering but when it clears up STFT1 starts adjusting but the LTFT1 is still at 25%

 

Just an update problem was a bad bank 1 o2