stalling in forward gears

What is your question?

My dads van started sputtering almost like bad plugs changed the plugs wires cap and rotor, still does it. When its cold it seams to run fine while in park but not in gear after it warms up it runs rough and misses and stalls,if you drive up the street it gets to the point were you cant keep it running however if you put it in reverse it will drive all the way home it will stall if you stop but the engine seems to regain a significant amount of its power back. I also checked for vacuum leaks and found none could it be the hall effect sensor? Also it has the 4 speed auto in it PS Im not from Beaverly Hills Im in Canada it was the only zip code I knew of the top of my head.