89 Chevy g20 stalling when slowing or stopped. What do I do next?

1989 chevy g20 dies if I slow
down, stop or put it in gear. I have
to turn the key to off then restart
it. I started checking the things
people thought up as follows fuel
pump, fuel filter, idle sensor,
checked fuel pressure, pvc, and
map sensor. It still stalls but
strangely seems to be slowly
getting better. Stalling less often
and I have discovered I can
control if it dies or not.  If im
stopped at a light In idle and it
starts to die I can pump or firmly
push the brake and keep it
running. My question can a
problem slowly get better?
Seems strange to me and what
can I check that would have to do
with the brakes? Im new to this
car fixing game learning as I go I
hope.  Should have taken auto
shot instead of home economics.  
Thanks in advance  Andrea