S13 sr20det AFR Ratio, 10.4 at idle?

[z31andrew]

Yo zilvians,

I have an s13 sr20det in my s13, just installed my innovate wideband/afr guage a couple of weeks ago, installed sensor about 22" away from turbo, it has been so nice to have! I have been trying to figure out my crazy AFR ratios before taking it into a shop.. i get about 12.4 at WOT in full boost at 14 lbs, and cruising. The thing that i have not been able to figure out is my idle AFR ratio, which jumps between 10.2 and 11.0. I tried cleaning the IACV the best i can, cleaned out the throttle body, cannot find any air leaks (just a driveway check nothing crazy), i've tried adjusting my fuel pressure between 42 and 52 psi, no real afr change at idle. My next guess is to try and make sure all grounds are solid. The guy i bought the car from let me know the fuel pressure reg it has installed has "acted wonky" for him in the past, but i've been daily driving the car for about 4 months and i haven't seen an issue with the fuel pressure or pump. I don;t know where to start next besides taking it to a shop, which i am trying to avoid.

Here is a list of mods:
s13 sr20 black top
tomei 256 poncams
gt2871 spec jb turbo
z32 maf
customer upRev 2 rom tune from years ago
550cc sard injectors
off brand FPR
Walbro 255 fuel pump

Any ideas on where i can start next? Does this sound like a fuel pump or regulator issue? Any help would be greatly appreciated!!