If you haven't already you may want to try the Greasecar or Biodiesel Infopop forums, they have many more greasers.

To address your question: could you possibly have an air leak in a connection to your heat exchanger that is letting in air and causing the shake (poor idle)?

I wish I had that kind of heat in my car, I only get around 120*f before the IP. Good luck.

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Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K