Car stalls or shuts off

Hi, my name is Prince and I have had this problem with my car for three year now and all effort to fix it proved futile. My car stalls or shuts off when I shift pass neutral to drive, and when in drive and want to shift to park it stalls and shuts off again when shift pass neutral. It sometimes works will not stall when pass neutral but does that more often. I have taken it to numerous mechanics, changed the throttle valve body, changed the spark plugs, serviced the injectors, worked on the automatic transmission. However, all did not remedy the problem. Please I need your help.