Nasty misfiring\lag WOT 5.5k-6.5krpm

[Getsumadis]

Ok, recently purchased aUS spec 08 rs4 cabrio with 60kmiles, apr stage 3+ supercharger installed, silicone intake elbow. Otherwise factory stock. When first purchased the throttle body connector was loose and caused all sorts of stuff, misfire lag, limp mode epc\esp lights etc. Removed cleaned reinstalled throttle body and now there is still a lingering issue.
During Wide open throttle pulls in gear 2-4(doesn't happen in first gear, don't have location capable of checking 5th and 6th) between 5500 and 6500rpms I get a real bad lag\misfire until I let off or switch gears. All other driving is normal, can go all the way to redline without issue at part throttle.
No codes are popping because of it either.
Looking through past posts and comments I find everything from throttle position sensor, high pressure fuel pumps, mass airflow, fuel pressure regulators, vacuum leak, coils, injectors.
I have obdeleven pro but am very new at using it need some feedback.
I'm in the portland OR area if nearby.
Thanks in advance

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[Getsumadis]

Anybody?

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[Getsumadis]

Well OK, had a suggestion that it was cheap gas so I got shell 92 with a bottle of techron.
Within a few minutes there was a epc light rough running, misfire through whole Rev range, then upon shutdown cool down, freely turns over but won't fire... like at all
Codes popped before shutdown include low limit not reached fuel rail eng 1, random misfires on all odd cylinders

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[Getsumadis]

The fuel rail low pressure makes me think high pressure fuel pump(apr $1850 yuk) but the not firing on startup makes me think more along the lines of main pump in tank.
Just ordered new main pump, inline filter, high press sensor, low press sensor(Amazon $160 much better fingers crossed)

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