Another Cold Start Problem!

["Joe Governali" <jgovern1@twcny.rr.com>]

My 87 5KTQ has been failing to start recently..  at least the problem is
pretty consistent:

1) Start car (engine cold, air temp = 20 deg. F)     STARTS & RUNS FINE
2) Drive car for about 10 min, temp gauge reaches 1/4 mark (below half)
3) Shut car off
4) wait 1 hour
5) Attempt to start car - car sputters & coughs like it wants to start, but
won't "catch"
6) Apply starting fluid to intake
7) starts & runs rough for 8 seconds, then all is fine again...

    I tested the two temperature sensors (mounted in block and coolant
neck), and both are OK (check against new sensors - used ice-bath as a
reference - acheived about 350 ohms..)
   Tested cold-start valve electronics (light-bulb connected to CSV plug),
and electronic signal appears to be of proper duration (about 3 seconds,
then comes-on briefly again under moderate throttle while engine is cold)

***   Is there more that I should be testing other than the two temp sensors
and the CSV????  I'm not sure where to go from here, and the fact that the
failure is very consistent makes me really wonder..... ***

    My friend's 875KTQ will NOT start at all ... we're going to tear into
that beastie tomorrow (SAT)..  any advice would be EXTREMELY APPRECIATED!  I
know that this is an often-repeated question during the winter, but I was
not able to dig-up much concrete advice from the archives...

Thanks!
Joe     87 5KTQ 118K miles