Hi AFR....
What's your EGTs look like?
I presume you're running cold plugs.
Investigate fuel filter condition. If you have an intank pump check the 'bag' used as a fuel filter.
The controller could be throttling the fuel pump to manage AFR as well as the injector PWM.
MAF or MAP sensor may be having problems, verify a WOT pull without an air filter to see any change, if you get a change then that's indicative of MAP or MAF issues.
If you have a 5 volt output MAF/MAP sensor you can place a potentiometer across it and alter it's signal manually to get your AFRs adjusted....if that works you should replace the MAF/MAP.
O2 sensors may be going south causing the ECU to run best guess fueling.
Did you place a modified chip in the ECU?
Do you have laptop interface to the ECU for mapping turbo pressure vs RPM vs fueling?
I ran a hybrid weber 32/36 with a turbo pressure box manifold on the top with a throttle body injector feeding the 2nd throat of the carb on an 80's mazda 626, 2.0L, 5 fwd with a 2500lb copper clutch plate and a 1.5 ton truck master slave cylinder.. It was simply triggered by 5psi turbo pressure using a standard oil pressure sensor as the control. Ran rich at WOT but then....at WOT you ain't saving the environment, you're cooling the EGTs and your valves and running lower octane gas.
Eventually built an entire boost controller for it, from scratch....6 fuel maps, 3 open loop, 3 closed loop with traction launch control and AFR management with water injection interlocks. It had 19 menu items with up to 14 line items per menu and a manual . Then I had to upgrade suspension, brakes, radiator, oil cooling, deal with torque steering and pretty much ended up with a whole new machine at the end. Had one subaru part...the intercooler. Used to run with the Volvo S80 head to head, a dead match in performance. Had a one touch button for switching to hi performance boost mapping.