well, I think I just aquired a project for this weekend (as if I needed another one!) -- the 300TE has been getting the rough idle back, has a gas smell, and stalls occasionally hot at idle.
Sounds like I need to check the EHA (if they leak, they are bad, by the way -- they aren't working properly even if the mixture stays in control, and contribute to rough idle and throttle lag), and need to check the O2 sensor. At 206,000 miles I suppose I'd not be shocked it was dead! Especially since it uses some oil and had a valve job done at 160,000 miles.
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!