[Corsa C 2000-2006] non starting at wits end

[kryton]

hi all please someone help me I have a 2002 Vauxhall corsa c it turns over but not starting okay list of things I have done-
changed all sensors
checked connections on dials
checked all fuses ,relays
checked spark
replaced ecu
checked fuel pump
in fact done everything I can find on forums there are no fault codes immobiliser light going out
I tried old ecu chip in currant set up starts and then dies immobiliser cutting in
but with proper chip just turns over yes there's spark and plugs are wet

any help would be appreciated I am now at my wits end