Whay does it stall while driving and when it sits at idle too long?

I recommend that you have the fuel pump/filter checked. The problem you listed sounds exactly like the problem I had. Did it make a sound like, I guess the best way to describe it is a pump that ran out of fluid to pump. So yes my '96 LeSabre would act the same as yours, and somedays it would run fine. Today I got the fuel pump replaced and it runs great now, the mechanic said it looked like it was the factory installed fuel pump. Get more then one estimate because I have one place(Aamco) for $738 which is still within the acceptable range, and Brake Master quoted me for $425, and it ended up being cheaper then that! Good luck!