Here is my .02 cents of advice. I would get fuel pressure reading before starting, at idle and after shut off. Hookup the pressure meter to the fuel rail if one available. Sometimes it could be fuel pressure regulator. If the reading are abnormal it could be fuel pressure regulator. it is located on the fuel rail. mine is E420. I am not sure where it would be on E320.

Also, check if any of the vaccum hoses are damaged. white plastic parts are brittle after going through beating from the heat build up in the engine compartment. Do a visual check. I hope this helps.

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Kamal Atwal
2005 Triumph Bonneville T100 (Black/white) [Sold]
2007 GL450 (Dersert Silver)
2009 Toyota Corolla (Metallic Silver)
2002 Tundra V8 - 2WD (Desert Sand)
1995 MB E420 (Silver Smoke) [crashed, now resting in peace at Silverstar Recycling Center]