Here are the issues:
1993 Z with 178k miles stock motor. At 150K all of these parts were replaced/installed: MSD wires, NGK Iridium plugs, MSD cap and rotor kit, MSD coil, vacuum lines/hoses, EGR valve, PCV valve, IAT sensor, MAP sensor, O2 sensors. Car ran like a champ for a few months!

16k miles later, it stumbled/cut-out REAL hard a couple times and the engine died. Took the ICM to be tested, it was bad. Bought the cheapo brand, car starts, but at low RPMs under a load it misses. Back to parts store, bought AC Delco ICM, missing still exists but marginally better. GM dealership serviceman said bad OPTI was bad. Brand new Delco OPTI installed...still misses, no change. Back to dealership for 2.5 days of diagnostics...all of their testing showed nothing....everything working as it should. They suggested plugs and wires. New set of NGK Iridium plugs...miss at low RPM still exists, but once again somewhat better.

Here are my questions at this point:
Should I pay the money are replace the MSD wires and/or MSD cap & rotor again after only 16k miles too? Why did this all start when the ICM puked and didn't return to normal once replaced? Could something else happen during the few seconds that my car was choking to cause my low rpm miss?

To top it all off, the past 2 weeks the car has developed a NEW problem. I can be cruzing down the road and all of the sudden the car will totally miss/not-fire, my tach and speedo will fall to zero.....a split second later, car is running, gauges are reading again, car is in oh-$h!t mode, SES light stays on, fans stay on....car continues down the road. Once i stop, shut it off, it will restart like nothing ever happened, no SES lights, fans operate normally, etc. 2 weeks, 2 days, or 10 mins later it may do it again.

I'm at a complete loss on both of these issues. PLEASE HELP before I decide to run this thing into a tree and be done with it.

 

I would check all of your battery connections and grounds first. The thing with the gauges sounds like you have a bad connection somewhere. As for the miss, you may need to swap the MSD cap and rotor. I'm actually really suprised they put them on a new AC delco Opti... I wouldn't think the dealership would disassemble a brand new unit to do the swap.

 

I will check battery connections and such for the loss of power issue.

The GM dealership didn't install anything either time. I did all of the work myself. I simply took the car to them for diagnostics and/or suggestions because I had exhausted every other source I could find....including searches/posts here and a visit to Ed Wrights shop in Tulsa, OK. I have been fighting this thing for a couple months now. The Delco OPTI didn't come with a Delco cap/rotor...it was a cheapo brand. I had a choice between the new cheapo or my slightly used MSD set. That's why I decided to reuse my MSD cap/rotor because they only had 16k miles on them and worked perfectly prior to my ICM going out.

Are you suggesting that it was merely coincidence that all of this started when the ICM went out and that my cap/rotor (and plugs/wires for that matter) could actually be used up after only 16k miles?