You may want to look at one more thing. I had a simular problem that I chased for a couple of months. There is another symptom going on at the same time which made it harder to sort out, but when I finally got to the bottom of it, all it required to fix it was adding a lock washer and tightening a nut. The car would be driving fine then would stall and be completely dead. After a minute or two it would come back to life start right up and run fine. A number of members pointed me toward loose battery cables, and when I checked them they were clean and tight. I never noticed that the B+ wire was attached to the positive cable with a nut until much later. When I did, I found out that it was very loose, not even finger tight. I took it off, cleaned the wire and the stud, and the spot on the inner fender where it connected to the rest of the wiring harness, then reassembled everything with new nuts and washers and lock washers and the problem has never returned. I still have the other stalling issue on initial startup but I think I'm closing in on it.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire