Hi and welcome to our corner of the asylum!
I would ask do you know when the fuel filter was last changed out? They are out of the way & get overlooked. No SES light when you try to make it accelerate? Then the light goes out when you relent? Check CCM as it may store that soft DTC.
It sure sounds like it's starving for gas when you want the secondaries, but why?
2* injectors check Ohm readings hot. Ohm okay = good coils, but could be clogged tips.
2* injectors for fuel flow, could be injectors or fuel pumps. 55 PSI on rail is top of the range, FSM says 48 - 55 PSI. Check regulator hose for fuel, if fuel present regulator is N/G. Pump socks clogged?
2* vacuum system could have: a vacuum leak or bad actuators.
Collapsing air intake duct from filter housing to air horn.
These are some of the things you could look at. Not trying to make work for you. Are the injectors OEM, if so they maybe the most likely cause of the trouble.
Tom