I found a site that explains the jetronic system and helps troubleshoot it,,, here's the link
914 D-Jetronic Parts and Troubleshooting
It's for a porsche, but I tell you what, the 1973 450SL has a cylinderhead temperature sensor, that I think was part of the problem. It was dry corroded, a splash of PBBlaster and
the car starts and idles for more than a few seconds now. maybe 10-20 seconds, so I think I'm making progress. 2/4/12- THIS TURNED OUT TO BE COINCIDENCE