I had one of the mechanics at work scan my car, he came up with a bad EST. I replaced it, but its still runnning rough. What should I do next?

 

I take it he came up with a code 42 and you replaced the ignition module? If so it could be a problem along the wiring. Check the EST bypass wire (tan/black) for breaks or short and do the same on the white wire at the distributor. The white wire should have 4.75V on it when the engine is running. Also check the ECM ground wire at the distributor (black) for breaks or shorts. Oh crap, I just noticed you have a V6. Those wires colors are correct for TPI but I'm not sure for your motor. Don't have my manual on me right now so............could somebody confirm or correct me here.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 23# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Colors are the same on the 2.8L V-6, so I'd chance the assumption that they are the same on the 3.1L as well.

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Later,
Vader
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