Failed ECU?
 

I'm struggling with my 91 TII with a microtech LT8. I've had problems since first startup where it would try to start but couldn't fire enough to idle. I was eventually able to get it running playing with the stock idle map, but it seemed to be running off one rotor. It would only run rich and the cat started to glow red.

A few days later, it started and ran a little better, and all the sudden started to idle high. I pulled my foot off the gas and it idled by it self for the first time. I thought it was fixed, but the next day it wouldn't start, and eventually wouldn't fire at all - no spark.

Today, again, all the sudden the spark was back and it was trying to start. It idled rough as hell for a couple seconds and then shut off. No errors on the ECU.

Here is what I've checked:
CAS - resistance check ok
Coils - resistance check ok
Continuity check on the entire harness with no problems.
Ground check the entire harness with no incorrect grounds or shorts.
Test mode sparks and fires injectors
Replaced plugs, plug wires
Verified all connections match the wiring diagram

This all leads me to think I've got some sort of gremlin that causes problems no matter what I do. Do I need to send the ECU in to get it checked? The car ran for a couple years for the previous owner with the microtech.

No ideas?

Sounds like the fuel and timing might be way off. If you fuel foul a plug then let it sit long enough for the fuel to evaporate then you can get spark where you once didn't have it. I'd find a tuner to help you out.