I've noticed same problem on my recently purchased old 300D. With a cold morning startup, I wait for glowplug light to go out (...and wait, and wait)- turn the key with accelerator halfway down, and it fires on the first hit, giving me confidence that my GP's are all working well. Yet, when fully warmed up, whether I glow it or not, it cranks at least a dozen times, then comes to life with a loud clatter and plenty of smoke. Just this morning however, I seem to have discovered the cure. Drove car to 10 or more yard sales- so lots of warm starts. I found that by flooring the accelerator while cranking, it would start on the third or fourth crank without pre-glow, and without the big noise and smoke signal. I'm not sure if this indicates that there is a problem- it just seems like it needs lots of fuel while cranking when warm.

By the way- at one of the yard sales, I found a case of 24 cans of "Wynn's Diesel Conditioner" for 10 bucks!!!