GTV 3.0 Engine cut out/not starting
Was driving along on Monday, when all of a sudden I had a complete loss of power, managed to pull the car over. Tried to restart, and it ticked over for a few seconds and cut out.
Phoned the RAC who couldn't figure out the problem, thought it might be a fuel pump fault. He did check the relays and all were fine. Had to have car towed to local garage (non alfa specialist).
The garage hooked it up to the computer and it came with injector fault, he then told be he reset the immobiliser and after this the car was running ok, but with the injector light on. He then checked on computer again and it came back with no faults. He said if I use the master key I might solve the problem of the injector light being on.
I then drove the car to work with no problem. Then to the gym after work, then leaving the gym the car wouldn't start. I tried disconnecting the battery for a few minutes - didn't work. Then when I was just about to give up and call the RAC again, it started, with the injector light staying on.
I managed to get the car home ok, and was getting late so just left it. Decided to get the bus into work this morning.
I recently changed a the front exhaust pipe and lambda sensor, and also added some fuel addative as advised by garage as it just passed it's MOT retest on saturday after failing emmisions test midweek.
What would cause this problem?
I'm thinking maybe the MAF sensor? Or could it be a dodgey lambda? Or had the fuel addative done something? Or is it just some electronic fault and maybe the code needs resetting?
Any help is appreciated.