[scarceller]

Some feedback:
- Don't alter fuel pressure from the stock settings. Not a good idea to do this as it results in some fuel maps not working correctly. Plus it will never fix the issues your seeing.
- At WOT the stock chip is setup to be slightly richer at WOT in the lower RPM area, it's common on the stock setup to be rich below 12.8AFR in the <3000RPM area and then lean out above 3000RPMs. However it's common tuning approach by chip tuners to target around 12.8 to 13.0 AFR across the RPM range at WOT but to do this the tuner MUST tune the WOT fuel map, you can never reliably achieve this any other way.

EDIT: skip this point, just saw you are running a MAF not AFM.
- The other possibility is that someone messed with the spring tension in the AirFlowMeter (AFM). Often folks open the meter and loosen the spring tension a notch or 2. This is NOT desirable and should never be done! Messing with the spring tension alters the calibration of the AFM. For example: if you loosen the spring tension it will result in richer AFRs but not in a linear fashion. It results in AFRs getting richer and richer as air flow increases. I wrote an entire document on the operation of the AFM, if you want the doc PM me with your email id.

Looking at te dyno result in post #1 I do think a fuel pressure test to confirm your fuel pressure is in order. Low FP can result in those lean WOT readings. As for the AFR curve over the RPM range it's not that bad, it's not so bad that you went slightly leaner in the 4800 to 5500RPM area. What's bad is that the entire curve is to lean.

You also mentioned matched injectors? What do you mean? Are these stock injectors that where simply flowed to be sure they are all flowing the same? Or are you running some sort of non stock injector?

Also, are you 100% certain you don't have a dead cyl? Like no spark or fuel in one cyl? A dead cyl would result in power loss with lean AFR since the dead cyl will pump unburned air (lots of extra O2) into the exhaust stream and the WBO2 will read lean. You can do a quick test for dead cyl at idle just unplug the each injector, testing one at a time, will result in RPM drop and the RPM change should be the same for each cyl as you test each. Also if monitoring the exhaust stream in LHS bank (cyl 1,2,3) with the WBO2 you will see the AFR go lean as you unplug an injector.