RE:CAR GOES LEAN AT 5000rpm

[1hawaii50]

I just picked my car up from a "dyno tuner" after they had it for 6 1/2 weeks, and it cost me $1,600.00 and change, and they still can't tell me what the problem is. I won't name the shop, because I don't want to start a flame session, more importantly I need to figure out the problem. At 5,000rpm on the dyno, the engine goes lean. Adding more fuel into the motor via a flash chip doesn't help. They dialed up 65psi of fuel pressure, and the pressure held, but the motor still went lean. They replaced the in-line pump, saying it was bad, but the problem didn't change. I have a 1992 GT w/ a DSS 306, Edelbrock heads/intake, 1.7rr, Anderson B-21 cam, 42# injectors, MSD ignition/coil, plugs 2 heat ranges colder than stock, 70mm throttle body, Vortech S-trim w/Aftercooler, no FMU, Walbro 255 (high pressure)in-tank pump, Walbro 255 in-line pump, new fuel filter, and Pro-M 80mm mass air. The fuel lines/rails are stock. I'm wondering if I'm maxing out the injectors? The stock rails should be good to 550-600rwhp. My other thought is I may have a wiring problem with the in-line pump, and voltage may be dropping at the pump, causing it to lose volume. If anyone has any ideas, I sure would appreciate it!