Old transmission fluid doesn't have the same viscosity as fresh, so the control and operating pressures were off, and the flow was goofy from the old fluid -- probably too thin hot.

Some metallic "dust" is normal. Actual metal flakes isn't -- indicates excessive wear on frictions. The friction material has a glittery look to it about like semimetallic paint --becomes visible as "sparkles" as the fluid flows in the pan, more less vanishes as grey dust when the fluid isn't moving.

I'd say the new fluid fixed the problem -- worth a try in the 300D shortly, as it does the same thing (almost skips third under light throttle).

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!