Mine's been having hot soak starting problems every since I've had it, usually I can get around it, but it's a pain. I think there is a bad electrical connection in the car somewhere, because every once in a great while it will just flat shut off. Often I can get it running again before I even drift to a stop. Every now and then though it won't restart, for up to 10 minutes.
There's also EVERY time it's warm, and I stop somewhere for more than about 3 minutes, It doesn't want to start. When it does, I'll get steady continuous misses on from one to several cylinders. After free reving it for a little while, the cylinders start coming back in, one by one. The injectors look freshly installed, by a moron. They're different colors. I"ve only heard the injector cooling fan come on once, the car usually runs very cool, so I don't believe it's hot enough to trigger the fan.
I'm thinking I've got some kind worn out gummed up sticky injectors, new looking or otherwise, and a bad connection in an electrical circuit somewhere.(haven't cleaned up all the connectors yet) Anybody got any experience that would shed light on my current assumptions??

Edit: ign module has been replaced, no change. Wondering if maybe pick up coil in dist could be culprit.

 

Have you checked the spark plug tips to see if they are all the same? What color? Any build up?

 

Ah, no! When it is running,(most of the time) it runs so well I never figured it could be plugs, and have never had a plug out, or a wire off.... Valve cover hasn't been off either... I spose yer right, it would make sense to check something that simple, mostly cause it's so easy... I don't think it's likely, but on the same hand, this whole set of events isn't likely...

 

I don't mean the spark plugs are bad (though they could be). You said you think an injector might be sticking... a spark plug tip will tell you how the cylinder is running.

 

I've heard jim Lister say that old gummed up fuel injectors can stick hot only, but never seen it. That's what I was thinking. It would be worthwhile just to see if there's any correlation between fuel injector color and spark plug readings. It got 29.8 mpg driving back from Seattle 3+ yrs ago, and I didn't know it was a 5 speed, and drove it in 4th all the way...

 

Try putting some Lucas fuel system cleaner in your Z, that helped my Z a lot.
Other then that idk