Moon161 suggestion of a leaky fuel line (or perhaps the primer pump) is a good one.

How long do you pre-warm the glowplugs? How cold does it get at night? Do you adjust your idle knob up in the mornings? How long do you have to crank it and how many times?

Harbor Freight has a compression tester for ~$25, and besides a wrench or two, that is all you need for a compression check. It is not good quality, but sufficient to know if you have 200 psi, 300 psi, or 400 psi.

The vacuum line from pump to the brakes should not be black. This is oil due to a ruptured diaphragm in the vac pump. This is a safety concern and should be looked into. I swapped my vacuum pump diaphragm as my first DIY project on my car, and it was pretty straightforward. This is not the reason that you car has trouble starting.

If it shakes bad in the morning, it may be your engine mounts, your engine shock, perhaps your idle is too low, or perhaps the compression is low so it is misfiring on one or more cylinders.

Good luck.

__________________
1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).