I didn't explain above why you would have hard starts when warm but not cold given my hypothesis. If the vacuum is not being bled off by the ignition switch, it will stop fuel getting to the IP when warm. However after the car has been sitting for a long while the vacuum can bleed off slowly so when the car is next ready to be started there is no vacuum in the shut off line.

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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