HELP: Engine cannot idle

[simoncpw]

Hi all,

My X5 4.6is has been having this consistent problem. The engine failed to maintain at idle RPM after starting up the car:

1) Engine starts without any problem
2) as soon as engine is started and without touching the gas pedal, I can hear the car tries to rev the engine up/down slightly to try to get to the idle speed
3) but after a few seconds or so, the engine would shut down

- if I press the gas pedal, the engine sometimes would response accordingly, but some times it wouldn't, and the engine would stop eventually regardless.
- if I switch from P to D IMMEDIATELY after the engine starts, the engine is able to keep at idle RPM and I could drive the car as per normal (no problem stopping at traffic light, in P or N.. etc)
- usually this problem would trigger the "Engine Fail Safe Prog" message, but not always
- usually this problem happens after about an hour the car is parked (drive to lunch ok, but problem comes up after I return from lunch)
- but went out for the first drive this morning, the problem comes up immediately.

Since this problem started about a month ago, I've had the following replaced already:
- air flow sensor
- fuel tank sender (which happened to be not working properly at the same time)
- fuel pump
- fuel filter
- battery

Any idea what else this can possibly be?

Here's the video I took when it happened this morning.

Thanks

Simon