Ohhh, I thought you meant it won't even crank when it has the issue!
Humm.. that's interesting. Could be at the ON connection in the cyl.. once in a while just not making contact or something. Or else you could check the fuel pump relay.. fuel pump ground (dunno exactly where that is),
It'd be interesting to know, when it cranks but doesn't start, does the fuel pump prime then or not? If you're ambitious, next time it happens check the fuel pump power/ground, as well as perhaps the relay operation.
Tough one, I'm just kinda crap shootin here.
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