OK, this is going to get a bit more involved here, so I will do my best to describe it.
At the EGR plug you have 5 wires
Black is signal ground, you should have continuity between that and ground.
Gray is 5v reference signal, If no signal then test continuity between that wire and pin 29 on the blue PCM plug
Pink is part of the EVAP system, test between the plug and pin 68 on the blue PCM plug
Brown, test between plug and pin 65 on the clear PCM plug
Looks like there are 2 gray wires, you will need to test both.
Symptoms of a problem with the gray wire is lack of power, rough idle, and chugging
Symptoms of a problem with the brown wire is incorrect idle, cuts out, chugging.
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