I have a 90 dodge b350. It started this thing where we'd be driving and it'd just die in the middle of the road. Got to the point where it just wouldn't start at all. We replaced coil, plugs, wires, tps, pcm, and ended up adjusting the timing. It starts up beautifully now and idles smooth. As soon as you pop it into drive and start moving, it backfires and cuts off. Checked for a vacuum leak and there's not one. At a loss. Any ideas?

 

I just had this same problem. Changed the fuel filter and it continued. Changed the fuel pump in the tank and now it runs beautifully. Well that is when I can start it. I'm not a,mechanic by any standards but that is what worked for me.