My 350SDL, 147k miles, original owner, is all of a sudden, very hard to get started in the morning. I have to crank it 8-10 separate times to finally get it started. After it warms up it restarts just fine.

Glow plugs and glow plug module were repalced a week ago and all was well for a week. Tried replacing glow plug module again, no change, it still has the cold start problem. Glow plugs are getting 12VDC from the module when key is turned on.

Any ideas?

Thank you.