if when it cuts out then the dash all goes dark and it won't crank then yes its possibly a immobiliser / security issue
if the dash stays live then its more likely to be a engine speed sensor issue and if thats the case then I'd check over the wiring to the sensor for damaged insulation and corroded connections - if this is OK then consider replacing the sensor
I'd also check the condition of the ECM power fuses and relay for cracks and corrosion
do you still need help?
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