A/F is WAY off

Hey guys, I need some help on diagnosing a problem with my a/f that I am having.

I'll start with all the symptoms starting from idle and then going to WOT.

At idle, my a/f gauge is reading 13.8-14.3 with it staying around 14.1-14.3 most of the time. A week or so ago it was right at the 14.5-14.6 mark.

While cruising (not under load) it reads around 13.4-14.2 with it mostly around 13.7-14.1

Under light load (still cruising) it reads 12.9-13.8 with it mostly around 13.4-13.6

My BIGGEST concern is WOT. Last night I was getting on the interstate I went WOT. It started off normally around 11.5 and then climbed to the normal 11.7-11.8 range. About a second later it jumped to 12.2 and then to 12.4. I shut it down immediately and called my tuner. He said to check for loose connections under the hood. I found none.

I just had a header leak fixed on the passenger side (reading is from the driver side). My car was reading a/f normally before the fix. I wouldn't think this is a problem because a leak would mean it would run leaner. By fixing it, it should run richer. I also don't think it's bad gas since I just filled up with Shell V-Power 93 and I had 3/4 tank of gas left when I went WOT.

Any input is appreciated. Thanks guys!

What are the best gas stations? We have Exxon/Mobil, Shell, and Chevron that I know of. I've heard Exxon isn't great, but I'm not sure.

Yeah, I figured staying away from WOT was the best idea, but...

I just did a 3rd gear pull and kept my eyes on the fuel pressure and A/F gauge. It was pegged at 11.0-11.1 the entire time (up to 5500 rpms where I let off since there was a red light). Fuel pressure was good too around 60lbs (39lb injectors).

I am running a custom tune through RWTD (runnin' with the devil). The tune was spot on coming from the shop so i don't know what is up right now. I'm NOT blaming the tuner and have 100% faith that he can fix this. I might be doing a datalog and emailing it to him. I just don't know the parameters I should datalog