crappy running between 3-4k
 

This is somewhat in addition to my fuel pressure saga that I posted a few days ago. I found the fuel pressure was set about 10psi too high and figured this might be why I have hesitations. backfires etc. Sometimes on the highway the car will buck if I roll into it.

I turned the pressure down to stock and now the hesitation is worse and much more pronounced at 3800. This is at really light throttle. Also, it seems like boost hits a brick wall too around here at 3psi and if I try to push through then it stumbles like fuel cut.

The car never did this before, but that was 2 years ago and since then I've:

removed all emissions
FMIC
Parallel fuel w/walbro and aeromotive FPR

Car starts great and idles with about 17.5 in hg, so it seems pretty healthy. TPS is okay and pressure sensor checkout too.

Clogged fuel injectors from adding the AN lines and not getting it perfectly flushed out?
ECU ground hell?
Crappy S4 alt with underdrive pulley?
Wired open twin scroll?
Dead animal in my exhaust?
vented to atmosphere tial BOV?
Having to modulate boost with the right foot since the exhaust is opened up 3"

I'd really like to get it running well now, before I put the microtech in this fall/winter.