SR hesitation, stumbling, breaking up..

[DJ_Sunrise]

hey guys.. under full throttle especially in 3rd gear, once my car hits 4500 rpm it starts breaking up and losing power. occasionally in 1st even with partial throttle, it breaks up real bad past 3k rpm. when i shift under full throttle into the next gear the motor hesitates terribly, then takes off again. to start.. here are my mods..
z32 maf
aeromotive fpr
apexi suction kit
apexi power fc
apexi n1 dual
hks w/g actuator
forge unos mbc
blitz fmic
tomei exhaust mani
mr turbo outlet, dp
4ply silicone coupling, tbolt clamps

i changed the o2 sensor and spark plugs(ngk iridiums, HR 7) 1 month ago. fuel filter was changed about 2 months ago.

i thought it might have been a boost leak, so i reinstalled all the couplings and clamps and have them tight as shit now.. everything checks out with the boost. i also had a similar problem when my mafs ground was kinda shitty.. so i redid the ground.. still having the problem.. cleaned the mafs sensor, and plug. the breaking up started a few weeks ago, right after i did the aeromotive fpr kit from enjuku, but i didnt think much of it. at first the pressure was too high causing my car to sound like a lawn mower. after i redid the couplings, vac dropped causing the pressure to lower.. so i raised it back to 45psi. fuel pressure is set around 45psi w/o vac. off of the intake manifold as a vac source, i have the FPR and boost gauge hooked up together. at idle, my vacuum reads .65-.68 bar, and for whatever reason occasionaly dips to .60-.62.

im at a loss here.. to the best of my knowledge everything should be solid. do you guys have any idea of what else i can try??? to test my aeromotive fpr, can i turn the pressure all the way up, hook up my factory fpr, and see what happens?? i dont know what to do =( someone please help...

-Bart