I'm just now coming to the conclusion of my m104 cooling issues, this on a 93 300TE with the same m104 engine as your car (I also have a 94 e320 m104). Rather than recapitulating, here is the link to the forum thread:
http://mbca.cartama.net/showthread.php?t=30017
I don't go into the twin electric fans much, but certainly every other aspect of the m104 colling system is touched on. Maybe you'll find something of value in there based on my experiences.
Cheers, JAS