1998 dodge b 1500 van goes dead when you stop

Van goes dead when you stop. Not all the time but enough that you know there is a problem. I have change the dist. cap, coil, plugs, plug wires, pick up plate, rotor button, idle control value, and hooked fuel pressure gage to van and system held pressue when van went dead. Have been having this problem for 2 months and on 3 different times van back fired very loudly. Main problem with van is when come to stop will sometimes go dead and most time will start right back up but sometimes I have had to work with van for a minute to get to start back up. I have had it in 3 different shops and hooked up to computers and it does not detect problem. May sometimes drive van half and day and will not have any problem. Main problem happens when come to stop. I drive about 75 miles a day in town so this is a major problem for me because have to come to a stop alot.