Hi JMW, I haven't been on the forum for a long-time, but when I read your post, I had to respond. I had a similar problem with my 82 zx turbo about two years ago. It was so frustrating, I was ready to sell it for parts (and it is pretty pristine). A few months after purchasing the car I noticed an intermittent failure to start. As a result I would bring it to several Z shop in Los Angeles ( no names ), spend a ton of money on it it would work for a few days and the go back to intermittent failure to start. After going through a similar journey to yours, I made some progress. I learned that if I pulled the wire and set it next to some metal on the car it would intermittently send a blue spark. If it sparked, then it started immediately. No blue spark, no start and no way to determine if it would spark. Finally I sent it to Mike's Z Shop in Whittier. He kept if for almost a month. His first attempt was to rebuild the dizzy. I disagreed, but wanted to respect his opinion. He thought the problem was fixed, but wanted to drive her for a few weeks to double check. The it failed to start for him. He eventually realized that the ECU had a small hairline crack in it and if the temperature/humidity/whatever was right it would work and then it wouldn't. He replaced it with a used ECU and for the past two years it has been perfect. I love the car and it can sit for a couple of months and still starts on the first few cranks. This may not have anything to do with your cars problems, but I know how frustrating it can be. Hang in there and good luck. Larry G