Hot start problem, 87 5kcstq

[Burl Vibert]

Hi Guys

I'm getting quite tired of chasing this problem around.  Anyhow, the car

starts when cold, and restarts when hot if started very soon after
shutting off, but if left to sit for 5 minutes to 2 hours (approx.) it
occasionally just doesn't want to restart.  No sputter, nothing.
I first thought I had it fixed when I found and repaired a fuel leak,
and indeed things improved greatly and it hardly ever happens anymore.
Next I found a vacuum leak and repaired it.  Problem still pops up
sometimes now, like right now actually, and occasionally there's a bit
of sputtering under hard acceleration.
There is plenty of spark, I can hear the fuel pump whining, the idle
control valve is humming along, it just will not start.

BTW, I just let it sit for an hour and a half and it started right up,
outside temp is about -3C.

Any suggestions?

Burl Vibert
1987 5000cstq (finicky)
1983 Coupe (reverse died last week)
1983 911SC (stashed away from winter)