1992 GMC S-15 runs too rough to drive and check engine light is on

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1992 GMC S15
4 CYL
2WD
AUTOMATIC
95,000 MILES

1992 GMC S-15 mileage: 95,000. I am having a repeating problem with ECM. Engine check light comes on. Engine runs so rough I cannot drive it. Original problem occurred driving 60 mph on freeway, engine light came on, lost power but made it ten miles home. The computer code is always 2-3 (mixture control solenoid). Over last five months I have replaced: mixture control solenoid, oxygen sensor, ECM (3 times), entire carburetor, added ground wire from ECM to firewall engine to firewall. It has been to a local shop and to a Chevy dealer. The truck has a remanufactured long block with about 5,000 miles on it. New fuel and water pumps were installed at engine replacement. Within last eight months alternator, starter, and battery were replaced. The truck still does not run reliably. ECMs have been lasting three to thiry days. I tried to find a replacement wiring harness and its not available from dealer. Any suggestions?

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After reading your question, the only thing we can think of is something else is causing the ECMs to fail. What comes to mind is AC voltage from a bad alternator from a leaking diode, or high voltage (from the coil) somehow is getting back down the wiring harness to the ECM or bad plug wires next to a wiring loom or stray high voltage in the distributor getting into low voltage wiring.