1987 Aw11 4age small port. Starts, idles then cuts out.

Hello,
I am using the BGB for diagnostics, but my car is not standard so it's worth asking for second opinions. Car is new to me and has not run since I owned it. 1st repair job was a new fuel pump and filter. Old one was seized due to rust and a broken filter screen. Replacement sounds fine, pulls normal volts and current and shifts fuel as expected. Fuel lines were blown clean and only had a light white dust residue in them. So either there was something else wrong which lead to the car being laid up and getting stale fuel or the long layup has caused a new issue to appear.
 

• VIC registered car from Hobsons bay
• Small port 4age.
• Big port ECU and loom.
• TVIS vac line is plugged (I am not sure if there are other deletions).
• Cyclops 661-3 Immobiliser.

 
The facts:
The car cranks fine and fires promptly off the throttle. It will then idle smoothly, running up to 1600 rpm (20 deg C outside) for 3-8 seconds and then just cuts out. No misfires or stumbling. Same happens with the fuel pump "on" by service port hard wire bypass. There are no service codes in play. There is a new battery and its been on charge between attempts. The immobiliser transmitter locks and unlocks doors ok without siren and the dash LED goes out. Its got 18L of new 98 octane fuel. 
 
Observations:

• Opening the throttle to try and catch it doesn't make much of a difference.
• Spark looks fine, plugs look fine. Timing light seems normal (No misses).
• Starting with the bonnet (immobiliser pin switch) closed makes no difference.
• Fuses and relays test good. EFI Relay feels quite warm to me, but I have no experience with the metal bodied round ones so I dont know whats normal.
• It has an oil leak from distributor.
• ECU B+ voltage stays good during stall.

 
There are lots of possibilities, but the fact that it starts nice and idles should narrow the field down. Does the ECU still log error codes if the engine has just started and hasn't gone steady state yet? Any suggestions to what's going on? Anyone else got the same immobiliser?
Regards,
SteveB