I have a vectra 1.8lt 2001 .The car and spanner light came on about 2 weeks ago as i was driving along the engine started to missfire then cut out all together. Rac came and did a diagnostic and got two codes saying immobiliser .car went to a garage but in the 3 days they had the car it did not cut out but they did change the ecu relay car seemed ok for a few weeks . Took the car out all fine parked up about 1 hour later got into car it started but the car and spanner light came on pushed down on throttle nothing there, turned car of and on three or 4 times then it started light went of and power to the throttle can back,drove home ok, then 2 days ago had a short drive all well parked up with engine running after 20 minuets car miss fired then cut out again, it started again with first turn of key but light came on again and no power to throttle. Shut of engine tried 3 or 4 times turning alarm on and of then car started no light power to throttle.I have been told it could be my engine ecu breaking down. Looking for advice please.

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