I have a 92 400E with a replaced wiring harness that has always run fine. Recently as I accelerate the power will suddenly cut out for a split second, come back, then cut again for a split second.....on / off / on / off..until I reduce the power. Then it drives fine.
I has a new harness, distributors and rotors. It feels like the ignition or fuel is cut then returned. No codes.
It doesn't run rough or misfire, it quits...then comes back and if I keep accelerating it keeps doing it until I relax the accelerator.
Any ideas ?

plugs, wires and/or coils will cause that. under load, the ignition can't keep up. you say new distributors and rotors-i ASSUME you mean CAPS and rotors. good luck, chuck.

If it was a wire or a plug or coil it would be a miss......this drops right out. Like some how the ignition completely stopped working then started right back up again. And it keeps doing it as long as I got my foot into it.
Like a circus ride.

While replacing the wiring harness, you may have disturbed the ETA cable as it runs across the top of the engine. The ETA cable has the same defective insulation as the wiring harness. Does your car have ASR? Maybe it's the ASR malfunctioning under acceleration. It's just a thought. After I replaced the wiring harness on my old 400E, my cruise control stopped working and I discovered that I had disturbed the ETA cable in the process. The ETA cable carries the signal from the computer module box to the EA/ISC/CC (engine acceleration/idle speed control/cruise control).

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

You're right....that's exactly what it feels like. As if the ASR was coming on and off. Only problem, this car doesn't have ASR just ABS.
I know the throttle body harness has the same problem as the engine harness.
Was hoping to avoid pulling that out.
It may be the computer.
Going to check fuel pressure right now.

You checked all the pins and no codes? No "fuel safety shut-off" code on pin 7?

Yes...I do get the fuel shut off
...here are the codes as of this PM.
Socket 7 shows fault 6: "starter lock - out...." that's kinda weird !
... and, fault 11:"Closed throttle recognition signal to ECM....." and "Fuel shut off to ECM.....(HFM-SFI or left or right LH-SFI)"

Socket 4 I get fault code 4 "voltage at mass air...open or closed circuit"
and code 17..CAN data: "Electronic accelerator control module - no data"

What do you think these are pointing to?

Wow, it's pointing to a mess. Just clear them and start over, see what comes back first.

Yeah...I planned on that tomorrow.
I was thinking it maybe the ETA....but it definitely "feels" like the fuel is shut off for that split second it hesitates.

You're lucky you have no ASR. I suspect you have probably already done this, but have you changed the fuel filter?

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

I'm going to do that, change the filter, to-day.