Are you sure it is a '93 with a '93 3.0l engine?
Does it have a distributor?
If it does then I can't find a Blue/Gray combo in engine wiring harness, but only go up to '91 wiring.
Gray is usually a sensor wire, just can't find the blue until '95 wiring, see below
Blue/Gray wire plugs into the Crank Position(CKP) sensor.
It is behind and just above crank pulley, so below alternator
CKP sensor tells computer that crank is turning and tells computer when #1 is at TDC so it knows when to time spark and fuel injectors.
If there are no CKP "pulses" then there is no spark and no fuel, so no start
3.0l Rangers got CKP sensor and lost distributor in 1995