I've posted about my problem before, and I still have the same issues about  
starting, but now I have established a pattern.  My car starts fine in the
morning, but almost like clockwork, when I go to start it after work, or at
lunch, it cranks but no start.  May take about 10 tries, then it just seems
like it catches and starts up.  After that, if I start and stop it, no
problem.  Starts the next morning, and the process begins again.  My shop I
go to had a known working fuel pressure regulator that he replace for me,
and no difference.  I have replaced almost everything that I can think of
except the fuel pump itself.  I hear it engage when I first turn the key in
the morning.  One thing I do notice is that when I am cranking the car, if
at first I step on the pedal and keep it depressed, it helps out and the
car starts.