I got the parts today
R&R'd the combo relay (fuel pump,etc.) and replaced the fuel pressure regulator.
Took me a few minutes to figure out how the regulator comes out
- but once I did it was easy.
Make sure you have something to compress one of these spring/ring/clip type of things - I used a pair of pliers but it was not too easy.
The fuel Pressure Regulator that was in there was a Mercedes unit and the replacement is a Bosch unit rated at 3.8bar.
Could that be it? I HOPE!
I started it cold twice and fired up perfectly and warm three times and all 3 times, it started without any drama.
If anybody knows any other things I should look at that don't cost too much - feel free to suggest.
Thanks again everyone