Ford 7.3L Power Stroke (1999-2003) :: 2000 - Bad Miss Or Stutter / Knock At High RPM And Deceleration

2000 F250 7.3L ZF 6spd 4x4 regular cab long bed 253k

DP F6 chip, 4" exhaust, WW2, EBV delete

I run 5w40 Rotella Synthetic. Oil was changed about 1,000 miles ago. I also added a quart of Hot Shot stiction eliminator. I use Power Service and Stanadyne lubricity in every tank. Fuel filter is new.(motorcraft)

For a month or so its been acting weird. I get a stumble/miss/stutter, at random, but mostly under hard acceleration and high rpm (specifically approx 2500-2800rpm). It will also do it on decel when I lift after accellerating . Recently, I noticed it is also idling roughly. The engine is shaking and it feels like a miss. When it does its "thing" it sounds like a single "knock". Occassionally, it sort of sounds like an injector "buzzing". I've been using the "stock" tune for the last few weeks, to minimize any chance of engine damage, as I have to drive it. Turning up the chip makes the problems more noticeable and happen at a lower rpm. The truck has plenty of power, and pulls hard, except for the "stutter". If I hold my foot in it to "push through" the initial stumble at 2500 or so, it will keep going a few hundred more rpm, and then really start bucking.

There are no meaningful codes. I DO have:

EBV related soft codes - makes sense since its deleted.
Overboost related codes- from turning the chip up - won't happen in stock setting
A soft code for the back pressure SENSOR. I have a new one and will be cleaning the tube when I get a chance. I unplugged the sensor and it made no difference in the miss issue.

I have recently done the following in pursuit of a solution to all this:
New IPR (autozone) valve and pigtail
New ICP (motorcraft) and pigtail ( sensor had oil in it)
New CMP and pigtail. (2 actually. First a standard pc139 for the obs, and currently a Napa echlin correct for '00) No change. Although it initially had the dreaded Ford small head light grey sensor and failed cct for #3 & 8. After the cps change, it passed cct.

Accellerator Pedal Position Sensor. It would not read any higher then 3.95v at wot, and only 0.50v at idle, so I installed a new one. After adjusting it a little, I have 0.76v at idle, and 4.02 at wot. Didn't affect the stumble issue, but it seemed to greatly improve/eliminate my parking lot speed "bucking".

I just did the UVCH's. The passenger side was pretty much unplugged. But they all looked good. No burnt, melted,or chafed wires anywhere. I probably could have just plugged it back in, but I changed both sides with new Motorcraft parts anyway. I did the gaskets and the uvch, but not the engine side harness/pigtail, as they looked ok. I also did the 0.50 mod as a preventative measure. After seeing the unplugged harness, I really thought this would be the end of the problem, but its not. Very frustrated.
As a side note, I was surprised to see that I have 8 AD injectors, and not an AE in cyl 8.

I have an old outdated snapon scanner. Its only good up to '99, but I am able to scan my 2000 as a '99. I think I'm missing some pids though.
I can do cct and buzz test, but no PERDEL readings.

As far as ICP, it idles at about 450psi, at approx 12% IPR dc. On a brief 2nd gear wot run, it will hit (and hold as long as I have road to stay in it) a little over 2900psi, at 41-42% IPR duty cycle. I did notice, during these near instantaneous stumble events, ICP would flutter on the scanner about 75-100psi. Its almost too quick to even see it.