This past weekend my 95 E150 van developed an occasional "stumble". It was like it lost electrical power to the engine suddenly for a split second. Did it three times in a hundred mile trip. Then this morning it did it again, but this time it cut out for a second or so, and this happened 3-4 times. This evening, on the way home, it ran flawlessly. Motor is a roller 351W,( speed density system) never been touched, only tuned up a couple times. 150,000 miles on it. Plug wires are Ford Racing 9mm and are a couple years old, ditto for the plugs, cap and rotor. All other parts on it are the original pieces. Any one got any ideas?