If you've had that many issues with ECUs to me is seems more like the issue might be elsewhere. The chance of getting that many faulty ones in a row seems pretty unlikely. If it will crank and not start it could be a cam or crank sensor problem. Could have been flakey with the first ECU and then went out for the later ones you tried. When in doubt I'd check the wiring to those to be sure they are getting reference voltage and ground. When I first installed my MSD to run my ignition on my carb setup it wouldn't start brand new out of the box. Found out the ground wire had pushed back out of the connector and wasn't making good contact.
And even though those computers are CAN based, they should still send out OBDII codes you can read with a code reader if you have the port wired in. The cars the ECUs came out of had OBDII ports, so there's no reason they shouldn't still work. That could give you an idea if a sensor is throwing a code.
