Driving into work the other day the car started misfiring and having lean spikes according to my wideband. Got it to my parents house and it started backfiring thru the exhaust pretty bad.

I'm throwing 2 codes:
code 83-something to do with traction control.(always had it)
code 42-est grounded. It keeps popping up even after erasing it.

Here's what I've done so far:
Had the ICM tested at the parts store.(it was good)
Swapped coils with a known good one.
Tested the wires going to the ICM.(all readings were within spec)
Checked the ground for the ICM.
Checked fuel pressure.(it was good)
Opti was replaced about 1000 miles ago.

I didn't locktite the screws on the new opti when I put it in, could they have come loose and created this problem? I'd like any other suggestions before I pull things apart.

 

Forgot to add that it doesn't sound like a constant miss, not like when a plug wire gets burnt. It sounds like multiple cylinders are off at different times, if that makes any sense.

 

Look the codes up on Shoebox's list. DTC 83 is a tranny code (reverse lockout solenoid - is it hard to move the lever into the reverse gate?). 94's did not even have traction control available.

http://shbox.com/1/Dtcs.htm

DTC 42 is indicating a problem with the ICM circuitry. May be intermittent... may explain why it feels sort of random. While the code indicates a short or a grounded circuit, its a fairly complex code to trouble-shoot. You need to get the DTC 42 diagnostic logic chart and work your way through it. It can ultimately lead back to the PCM or possibly to the Opti. Did you have the ICM tested while it was hot? They tend to suffer from heat soak as they age.

 

I didn't have the ICM tested when it was hot because the parts store is to far away. I wouldn't think it would matter because it's running poorly even when cold.

I also did the ICM tests on shoebox's site and everything looked good.(is this the code 42 trouble chart you mentioned?) I even shook the wires around a little bit to see if there was a loose connection somewhere. I'm probably going to replace the ICM anyway just because it's the only thing in the engine bay that hasn't been replaced before.