I've got a '99 S70 naturally aspirated automatic with 155k on it.

At first it would stumble and stall only in heavy traffic after a few minutes. It has been getting worse and now will stall at idle in the drive way, while slowing down to make a turn, etc. It behaves itself perfectly above 1100rpm and when cold.

After stalling it takes substantial throttle to restart/keep it running.

Every time it stalls it throws a P1081 (immobilizer code) from module 7A

I SeaFoamed the throttle body, ran a bunch of injector cleaner through it, gave her new plugs, air filter.

Disconnecting the MAF causes no change in behavior (other than it will also throw a MAF sensor voltage low and IAT voltage low code as well)

Is the immobilizer kicking in at inopportune times?

Any help would be hugely appreciated.
Cheers,
O

 

The immoblizer only works on start up then it is disabled.
You have another problem. An immoblizer will not stall a car.

The throttle body might be bad.