Stalling on the Freeway

[foxxinabox at wideopenwest.com (Foxx (in a box))]

   Having to sit in traffic for nearly an hour today the '85 began to 
stumble and then died. As the traffic was due to an accident ahead, the 
whole interstate was closed. I tried to start the car and it coughed a 
couple times but nothing else. The coolant temp never even got about 
half way. On a whim I yanked the fuse to the fuel pump and let the car 
dry itself out. After a few more minutes of coughing it finally caught 
and I was able to go again. Problem is that when I came to a stop the 
car died again and resumed it's non-starting issue. Mind you, the 
weather was quite warm today and I don't have these stumbling problems 
in cooler weather. What could the outside temperature be affecting so 
that the car would run rich to a fault?