SR swap, white plugs lean

[boost135]

New to the forums and SR's, but have done a few months worth of searching on this. There are all sorts of possibilities but I'd like to find out what my best next step is in diagnosing. I need to be careful with funds as I've been laid off since buying this car. I know join the club, right?

The only two ways I have to watch mixture are an EGT gauge and by looking at the plugs.

Mods on the car are a GT2871r, Walbro 255, nismo fpr set to stock idle psi, sti 550cc injectors, and a N62 MAF with a Emance chip. I'm on the second Emance tune and it was set to support 18 psi on my setup. So far I'm trying up to 15.

The one visibly wrong thing in question is the 02 sensor wiring. I'll run new wires for that soon but is the mixture even effected by the 02 sensor readings at full throttle? The car is pulling pretty strong at part throttle, it's only at full that it gets weak and reads 1750 degree EGT's. I tend to believe my gauge and probe since the plugs do get white when pushed at these temps.

Something else that's making it difficult to diag is that I'm not able to get the ECU into diag mode by turning the screw. I can do this on my other KA car without a problem. Jason at Emance told me that not being able to set into diag mode is a sign the ECU is in limp mode. The car revs up to 7K though, so I'm not sure about that. The CEL is on so I know there's a trouble code in there.

Even turning the fuel pressure way up hasn't lowered EGT temps. I read high EGT's can be a sign of retarded timing and not always from a lean mix. My base timing is set correct so possibly whatever fault I have (maybe 02 wiring?) is causing a timing pull back? I have checked for boost leaks as well.

I've read that having a wideband to confirm and the wiring modded for a consult port and a consult program to run are things that could help greatly with this. I'll post locally to ask about running consult or to ask about swapping ECU's for a drive. I can't really spring for those now so I'm wondering what other suggestions you all might have to try to solve this one before I go for too many more test runs and crack a piston ring land : )