I have an issue that when you try and start the car from cold it cuts out straight away and keeps doing this but eventually it keeps running but very rough (bit like a misfire)and improves as it warms up. open throttle and it cuts out.

Was running ok but now it has been stood it has got worse and unable to drive even when hot.

Only fault code occasionally is P1570 Immobiliser, igntion seems ok, fuel pressure ok, all live data looks ok (AMM,IAT,CHT etc).

Valve timing has been double checked as it had head gasket repair just over a month ago and has been running fine ever since up to now.

Crank sensor replaced by customer and ive scoped camshaft sensor - both seem ok.

Has anyone had any similar issues as there does not seem any clues to proceed ?