lack of throttle response below 2300 rpm

[hoptwoit]

I have aquired a 2003 ford F 450 M/T weight is 13500 lbs (big service body on it). The engine has 230000 kms or a roughly 120000 miles. The engine is slow to accelerate between 1200 to 2400 rpm. Some days it's worse than others and almost sounds like its starving for air or fuel. Once it hits 2400 comes alive and pulls hard.
It has.
1) New black CPS and passes all cylinder contribution tests.
2) DIY injectors found a couple of broken springsbut all else looked ok.
3) New ICP sensor.
4) New injector pressure regulator.
5) New HPOP.
6) New air filter.
7) checked exhaust for leaks none found.
8) Checked intake for restrictions none found.
9) Boost pressure max with red line hooked up is 14-16.
without it will go up to 19.
10) Map sensor checked against via computer against a direct reading gauge and numbers match up.
11) Dropped tank found screens 50% full of junk cleaned sceens and replaced tanks.
12) exhaust backpressure device is working normally.
13) Throttle pedal reads on computer smoothly though it does not show 100 % ( is that normal for auto enginuity program)
14) There are no codes.
15) Fuel filters all changed.

The engine starts well, has a smooth idle and pulls strong above 2400. just seems very slow to get there.
I have the auto enginuity program so if any one has any ideas I would love to hear them. Thanks in advance.

[hoptwoit]

Update: Truck warmed up in neutral if you try to slowly raise the rpm when the engine hits between 2200 to 2400 you get a little white smoke engine misses and will even start to loose rpm. If you floor it it does go through a rough spot and a little white smoke but gets to redline.

Could this be an IDM / PCM issue has anyone had a simmilar issue?