this is

and i am so
I have a 92 taurus lx sedan i've had the car for about 6 yrs kept good car of it
i got the transmission rebuilt about 3 years ago.
Now my problem is this.. When i First start my car up, it has no problem going into gear but once i drive it for about 5 mins it slips out. and wont go into any gear at all but Park. When i stop the car i can move the selector through every gear but nothing happens. It's not engaging and the motor isn't idling down. Almost like i never moved it out of park. I was thinking it was the selector but it has to be something else because when i let it sit for a long time it goes right into Drive. Somebody PLEEEAAASSEEE Help me before i go