[s-cars] cold starting problem again

[Jerry Scott]

I parked the 93 Urs4 outside over night in 2°F deg. weather for 9 hours.  As usual in this kind of cold, it did not start.  I checked injector voltage and all had 8 volts during cranking.  The fuel rail pressure was up to nearly 50 psi..  When I pulled the coils cover I found that there was no spark on any cylinder.  I applied hair dryer heat on all of the components and wiring under the cowl cover, but still no start.  I used the starter to pull the car back into the garage. After the car warmed for about an hour to 50 deg., the spark test showed a spark, (tested with a spare plug in the coil and a ground wire on the plug).  I reattached the coils & cover and the car started.  Conclusion is that something kills the ignition in very cold weather.  The CPS was changed about two weeks ago, so it's not that part.  Could a bad crank sensor maybe cause this problem?  Is there a diagnostic test for checking voltage inputs to the POS units? I've been chasing this problem for years and still have not found it.  The car runs great in normal cold weather, but when it gets near 0°F, it does not start.  It has never stopped running when driving in 0°F weather, but once it cold soaks for several hours, no go. Car has only 93k miles and I am the original owner, so I am resisting trading it for another car. Any ideas?
Jerry