I located the resistor on my '88 201/2.6 on the inside side panel of the battery compartment. It's a tapped up pigtail tie wrapped to a slot on the panel. My understanding is that plug in resistors are used to vary the timing on EZL ignitions that have the non-adjustable TDC sensor. My former '84 2.3 had a conventional adjustable distributor, but I'm not sure about the later 2.3s.
The original post has a link to another post that lists the resistance values and timing changes. No resistor means full advance, the US resistor is 6 degrees retard, and zero resistance (plug shorted) is 12 degrees retard.
I e-mailed the original poster and asked if he checked for any change in base timing. He did not, but reported better low end torque. I want to retard by initial timing to give me more margin on emission testing. My HC is at the ragged edge of the limit, but I don't have to be tested for another two years, so I don't plan on changing it until them.
If anyone does remove the resistor can you let us know if it changes the base timing. For my '88 it is 9 degrees and is always listed on the emission label. Different years might vary, but check the base timing before you remove the resistor and then again to see if it changes.
Let us know what happens.