PCA SDR

1982 924 Turbo generally runs great, and just passed smog. Sometimes when cold it will start, then immediately die.
As it gradually warms up, while restarting over and over, it will eventually stay running (It may take 20 minutes of trying).
One weird thing is the more it is cranked (and gets warmer), it will stay running longer and longer.
About halfway through the process of repeated attempts to start (10 minutes out of 20), it may run for 3 seconds.
Another note is that it runs fairly smoothly (all cylinders firing), then suddenly dies.
Also, fanning the throttle a bit doesn't seem to make a difference (so I'm guessing it's not the bypass valve?).
Once it finally stays running, it's happy and not rough at all.
This problem doesn't always occur, but when it does, the symptoms (and starting routine) are identical.

We've checked the over-boost switch, cold start valve, spark plugs, engine ground, and ignition switch. All okay.
I kinda doubt fuel filter, or other fuel supply since it runs so well when warm.
Ignition too (from distributor onward) seems unlikely.

Would definitely appreciate any helpful suggestions!

Paul,
Turn the ignition on.
Pull the blue 2 pin plug on the flow meter. (Looks like an injector plug).
This is the roll over switch. When you unplug it the fuel pump should come on and the frequency valve should come on. (Bzzzz)
Does it come on?
Lets say yes it does.

When the car has the cold start issue pull the roll over switch plug and see if it starts normally.