That drawe does seem excessive although I will admit to knowing nothing about your engine.
The strip fuse for the glow plugs I think is only 80 amp so 100 seems weird that it would even measure that high. As tot eh starter I am prety sure that there should not be that much current draw when it is trying to turn. Could be that the starters beginning to go on you... Sorry.
You might also check all yoru connections especially the grounds. If you have a bad connection on a ground it will cause all kinds of problems.

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique