The engine was retimed after the distributer change.

EGR passage ports where cleaned for the whole length of the runner with some wire. It was totally unimpeded except at some plug holes that were slightly clogged. The EGR seems to work fine. It opens and closes while reving the engine. Manually operating it at idle makes the engine die.

The cap, rotor, plugs and wires were changed after the problem appeared but did not solve it. The old plugs with about 20,000 on them were buring perfect. Infact some of the best looking I've ever seen. Nice light brown color, not wet and no excess carbon.

My guess is a sensor is faulty but not bad enough or often enough to make the ECU know it's bad. Or possibly it's the replacement junk yard distributer occasionally having a problem. The dealer wanted about $500 for distributer parts. The origional suffered a bearing and seal failure. I couldn't turn it by hand when I got it out.