From what I can understand you can be doing like 75 mph and it will just die right?
Well I had a 93 olds cutlas ciera and it did this same thing. We would take it to the shop it wouldn't do it cause it was so random. It did this for about 3 or 4 months when it finally died in the middle of a busy intersection (which I told my parents it was dangerous to drive because of this) and it would start back up. We had to sell it because none of the Techs could fix it at the Old's dealership.
I don't think it would be the distributor if it's just dying going 45 mph. If it were just dying at the red light then it might be the distributer.
Good Luck on this one. If you find out what it is let me know. I've always wondered what was wrong with that damn Oldsmobile. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/crazy.gif" border="0" valign="absmiddle" alt=':crazy:'>
Good Luck!
-Dave-