Location of engine ECM

I assume I have to remove the dash board to access it, correct?
I am replacing it because for the past 7 months the car has just be quitting on me. The 1st time it happened I checked and found I was getting fuel but no spark. I had to have it towed to my local garage. When it got there it started right up. The next time, same thing. Towed again and this time they changed the ECA relay. Then happened again so I changed the relay (carried a spare in the trunk). Happened again so I put in old relay, no help. Happened again, this time I removed the negative battery terminal for 10 minutes and it started right up. Spoke to my mechanic about it and he too says it could be the ECU itself, he suspected it when he was diagnosing the car earlier.
Your thoughts?
Thank you.

Roy,

Thank you so very much for the info. I have located it just by removing the lower dash panel.
I guess it will just pull out of the firewall connector? (Haven't tried till I get the replacement)

I have ordered the replacement ECM.
Since it is not programmable is there anything I should do after I install it for it to learn the system? Let the engine idle for a while or just drive it?
Thank you again.

Well, I have changed the ECM and still the same problem! I get no spark when this happens. I have also previously changed the TFI Module. What's next?

Thank you for the help. I will carry a multi-meter with me for the next time it happens.
The problem is that it happens intermittently, I never know when it will happen.
Most times the car starts right up. If not then I have to pull the negative battery terminal off for 10 minutes then it starts.
Will keep you informed.
Regards

Well, it has happened again, no start. This time I had all the test equipment with me. I 1st tried to use my code reader to see if anything showed. However when I did the KOEO I got absolutely nothing, would not even click all the relays as it always does. I did all the test points at the TFI connector and all were okay except for the ground, got an open circuit. I pre-checked all the test points when the car was working and now I read open at the distributor ground! Now ready for this:
I also brought along a spark tester and I have spark!
I also checked for fuel pressure at the rail Schrader valve and there is pressure.
If you have spark and fuel why is there no start.
Car will still not start after sitting for over 1 hour with the battery disconnected.
Any thoughts?
Could it be possibly the anti-theft module? I don't know how that disables the car?
Thank you.

I have previously replaced both the fuel relay and the PCM relay.
Today I did try to tap them both.
I do have spares and will take them when I go back to the car.
It is currently in the Walgreens parking lot about 3 mile away.
But I did check for voltage at the coil with key on and both terminals had battery voltage.
I disconnected the TFI module and had voltage at all test points except for distributor ground was open.
Will let you know when I go back with spare relays.
Thank you.

Well, I went back with the spare relays, changed them, no difference.
I also brought some starter fluid. When I spray it into the intake it tries to start.
Again, there is pressure at the fuel rail but I guess the injectors are not firing.
How can I check if the injectors are pulsing?
If not what could be causing them not to pulse?
Sorry for being such a PITA but I am at my wits end.
Thank you