Look at eBay or the junk yards.
This website has a lot of wiring for many cars including '92 Eclipse. http://www.modifiedlife.com/1992-mitsubishi-eclipse-car-audio-wiring-diagram/
Just go to Google and search for '1992 Chevy lumina wiring harness' up will pop 20 or a 1000 places willing to sell you one.
WIRING DIAGRAMS TOYOTA WIRING DIAGRAMS TOYOTA
A salvage/junk yard.
Im chasing the wiring diagram for 1994 indicator,lights,windscreen wiper arms
The wiring harness will not work. In 1992, Dodge introduced the "Magnum" series motors. These motors were MPFI (Multi-Point Fuel Injection) motors whereas the motor in the 1990 Dakota was TBI (Throttle Body Injection.) On this fact alone, you'll be missing the connections required for the fuel system if you use the wiring harness. The computer management systems were also vastly different so you would not be able to plug into the Engine Control Unit (ECU) with the wiring harness.
http://www.the12volt.com/installbay/stereodetail/1685.html try this link.
My 1992 Eclipse is doing the exact same thing, someone told me it might be the transmission computer or just the wiring. Whatever it is, this is really starting to irritate me.
ebay, from 9.99 to over 30.00 bucks
On most they have a built in amp so you need a wiring harness
depends on the generations 1988-1991 is,1992-1995is,1996-1999is, so on and so forth
Check tht injector wiring harness for loose and corroded connections.