We Have the same problem
 

My son and I went to view, and ended up purchasing an 80 928 in beautiful condition a few weeks back. I was a little argumentative with the seller as I know porsches pretty well, and he obviously did not, though he said he did.We drove away with it for only 4 grand even. On the test ride it ran like a scalded dog, though I could detect some rumbling from the rear. Tube bearings or Cv joints I suppose. On the way home, I stopped at a traffic light and it went dead. It had plenty of gas, but acted as if it was out. It turned over fine, but would not start. We pushed it off the street (angrily) and tried to start it for a while with no luck untill I poured a little gas into the intake under the air cleaner. It started right up and ran perfectly for a few days untill one night when my son drove it to work, and while leaving for home, it stalled again. I had prviously told him to get a can of starting fluid spray (instead of raw gas) in case it stalled again, which he used, and again it started right up. It has not happened again now for about two weeks. I suspect a fuel pressure problem, or relay problem, but the fact that you can squirt in the starting fluid and drive away seems to support a fuel delivery problem. I'm wondering if there is a technician who reads this post who has experience with this probibly common problem (like Roland?). Good Luck with yours, Christina, these are very sharp and well built cars!:p