Absolutely... The computer needs to know that the feedback that it's getting from the left 02 is actually the left 02, or it will keep adding or subtracting fuel to try to reach lambse. What side you install a sensor is irrelevant, but the left 02 must be plugged into the correct wire color for left 02. Same with the right. It would be nice if ford had made the connectors different, but unfortunately they didn't so you will have to look up wire colors to verify.. I have them written down somewhere but I'd have to dig.. and dig
On the 94 the O2 plugs are side specific IIRC. One is by the starter and the other is by the clutch cable. I don't think you can swap them since the sub harnesses cannot be moved that much.
