I have a 91 bronco with a 351W and I am having that same problem now except that it stalls every once and a while. I replaced the EGR and still had the same problem. So I took every fricken sensor out, sprayed the connectors down with WD-40 and put them on and off(to remove corrosion in the female end) and then left them on. I havent had that problem yet, but if I do I'll post it. Personally I think it was the 02 sensor. Make sure that the negative end of the battery is disconnected before you replace the sensors.