Hi Dave I would say that a long as the new EVAP valve as the correct Resistance , the next thing to do is by-pass the original wiring and fit temporary wiring for testing purposes.
give the EVAP valve a new 12 volt supply direct from battery. Run another back to the ECU trigger.
Now try the car again if the same fault returns, you have a Duff ECU.
One last thing though just double check the ecu plugs and make sure none of the connectors have been spread open buy other people poking in too large test probes.
HTH
Darren......................