Well there is two ways of looking at it . the computer has a bunch of fail safe modes in it , oxy sensor , airflow meter etc . When parameters get out of limits it fails back to fail safe mode , ie no revs above 2000 rpm .

If you pull the plug on the oxy sensor it should go to fail safe mode , if the sensor wa faulty it should run ok abit restricted . Dito on the air flow meter . I have had the engine running fine in the past without the airflow meter .

Now oxygen sensors only work when they are warm , hence some are heated . the ca18de I have is not heated ( turbo ones are ) . There is no way the sensor gets hot enough at start up to get a good reading , thus it should be running without it . I belive the computer ignores oxy until off idle and at full throttle etc .

I doubt the sensor could cause such a change in the mixture to cause it not too run . Have a few vehicles here running them disconeccted ( not ca18de's thou ) and they run fine , economy may be out the window but run ok .
This will not idle , I can only keep it running by keeping it above 3000rpm . Let it drop and it goes to crap , backfires etc etc .

So off to the shed to pull the AAC and IACV and clean them and try again

Cheers

Chris