Have you ever adjusted or removed the ALDA? That's what finally cured my sluggish 91.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I'm surprised nobody said anything about injectors.

They are not something I know cause the symptoms you mention.

One I missed was if there is an issue from the accelerator pedal to the throttle arm that keeps the throttle arm from going into the position it is supposed to be in that will slow you down.

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84 300D, 82 Volvo 244Gl Diesel

Probably because injectors won't cause the problems you're having. They'll cause noise, they'll cause smoke, they can cause rough running, but not low power.

You have a fuel starvation issue or a boost problem. You mention nothing about ever replacing the spin-on fuel filter. Low power is a classic symptom of one that's beyond time for replacement.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

I replace the filters on a regular basis. I think the big one is supposed to be changed every 12,000 miles and the small ones 3x in between, so every 4k miles.

Purging them would have no effect.

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84 300SD
85 380SE
83 528e
95 318ic

No, I never removed the Alda and I don't know how to adjust it.