Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Have you taken a fuel sample to insure that there isn't any water/contamination or turned fuel in the tank?
Are we 100% certain the ecu you switched is good? The reason I ask is that there is a specific issue with the ecu we see on this model.
Knowing the pressure is good, the fuel is good, and since it runs on ether that the compression is good, we have a very small range of possible causes here.
Let's take a noid light and check for pulse on each fuel injector connector while cranking.
With it running on ether we know the ignition and compression are all okay, putting us at a fuel issue of some sort. With the fuel pressure and quality good, really our injectors/injector control are the only real suspects here.
Do the noid light test tomorrow... If there is no reaction, double check your 12v supply is good (fed off the mfi relay, so a fuse issue is not possible). If 12 v is there but no pulse, trace your wiring back to the ecu for damage and if nothing is found, consider the possibility that the replacement ecu had a problem. It is worth noting that the 91-94 ecus were famous for a multitude of problems, not the least of which was injector driver failure (usually as a result of capacitor failure).
If there is signal to each injector then we would have to consider a problem with either the injectors or the fuel rail preventing the fuel pressure measured at the rail from entering the engine.