Alright guys,
I'm getting some greys with this car.

2002 Mustang gt, long tube headers, catted xpipe, under drive pullies, 1 piece dragon plenum/tb, bbk CAI.

After the car warms up, and I accelerate passing 3500 rpms... it coughs/looses power, then struggles.
If i accelerate very slowly, i'm okay... but if i'm merging on the highway and give it throttle... as soon as i go over 50% throttle it coughs and i lose power and the car jerks.
I've changed the spark plugs, cleaned the MAF and the TB, smoke test for intake cracks - nothing, no issues with coils, oil's good, just did a back pressure test on both cats - perfect, put fresh shell 91 octane. Still does it. I unplugged my fuel pressure sensor last night and drove it, for a minute she was doing good! Then after about 5km she started acting like she had covid.

What else can I do? Could it be the fuel pump? Anyone been through this nightmare?