I think holding 1st gear longer could be explained by the fact that you have to push down the accelerator farther when cold to get the same horsepower out of the engine. This would delay the shift. I can't explain the flaring. Lower vacuum should make your shifts harsher, not softer so I don't think a leak can account for it. Maybe it's time for one of the shift kits.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13