2000 Blazer Temp. Related Starting Issue

Greetings..
 
I have owned 3 Blazers between 96-2000 now - and have peformed most of the typical chores that seem to go with fixing your own blazer.  This one has me scratching my head....
 
If the weather is warm (80+ ish) - It has no problems - It starts and runs like normal
 
If the weather is cool (like 70ish or below) It does not want to start right away.  I have however discovered that If I dump a half cup of gas into the carb - It will start and run fine from that point on.  Through the rest of the day - even If it sits for a few hours - it will then start again fine.
 
I Have good fuel Pressure.  I have no codes.  I replaced the fuel filter.  I replaced the temp sensor next to the Mass Air flow sensor. 
 
This is deff a fuel issue - but it is whatever controls the flow of gas when the starter is engaged - and is affected by the outside Tempurture.
 
Any thoughts???????
 
Thanks in advance!!!
 
Charlie