I think they are both good. The o2 sensor has already been replaced before I bought the car and I cleaned the catout too. I whent ahead and replaced the ecm but i cant get it started because its not getting any fire now and i have to fix that problem. I replaced the coil pack on it already but there is something else causing it not to fire. Maybe the power transistor?

 

it could be the transistor.. have you checked it? this thing happened to my car before, it turned out that my mitsubishi oxygen sensor was bad and needs a replacement.

 

[:-]I'm experiencing similar problems with my 2.0 GS.
I too, replaced the coil, transistor, wires, plugs, air/fuel filters, and no start for me either!
I just checked the ECU per the Haynes manual instructions, and for a CA. Car, 2.0, para. 6 states if the sweeps are constant and continuous, the ECM is OK!
I just don't feel confident that the instructions are on the money, and/or, I performed them to spec. to say the ECM is bad.
It was replaced, according to the guy I bought the car from, two years ago.
What I'm amazed about, is the fact that Chrysler/Mitsu didn't use a ECM that uses LED's to code read, instead of sweeps of an anolog multimeter's needle!
I'm scouring this site in hopes of finding info that leads me to remedy my problem. Otherwise, I just may put this little car back up for sale as soon as I get it running again, by hook or crook!
I'll then start my quest to find a commuter car, good gas economy, all over again, and focus solely on Toyotas or Hondas?

 

The power transistor is good i checked it just the other day. The transistor that my car has is the same as like the 91 model. But I checked it the right way. I am getting fire to cylinders 1 and 4. I thought it could just the coil that i bought bad for the number 2 and 3 but its not. I mess with the car all the time and still cant figure anything out, but im also not the best mechanic in the world. Could the O2 sensor really be the problem?