Engine barely runs (MAF/O2/Relay/Pump) issues

[jamesb]

Hello! I am a long time lurker, but only just registered.

This forum has been a great help in helping me diagnose issues with the A8 and felt it was time to actually sign up!

I am trying to diagnose a fault with the A8 - basically it cut out one day and wouldn't restart. Got the car recovered and suspecting a dead fuel pump, installed a new unit.

After installing the new pump the car ran briefly, idled nicely and even revved up a few times before starting to stumble, barely tick over and then stall.

So potential causes -

Bad 372 relay?
Bad MAF sensor?
Dead o2 sensor? - A precat sensor had failed, maybe the other one has gone as well?

Is there anything else on the A8 that may cause these issues that I haven't thought about maybe on the ignition side, additional engine control sensors etc?

Any insight is appreciated.

Regards

James