My '99 E300 has one plug with high resistance, and GP light stays on, along with CEL. Does anybody know which wire goes to which plug? My bad plug is on the black-and-blue wire, the one on the top, toward the driver side of the connector. It has to be #1,#3, #4, or #6, since it's on the end of a row of 3 wires. I guess it would be easy to find out if it's #1, as #1 looks to be the easiest to access without removing the intake manifold, although I haven't removed the plastic pans underneath to see if any others can be accessed from below.
Steve

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1980 300 TD

1997 Dodge Pickup/Cummins 5.9 12-valve