2001 range rover 4.0 Stalling- Stop at junction..idle..revs drop..occasionally stalls

[rangerover2001]

I have a 2001 range rover 4.0 HSE which has a problem with the revs dropping, almost to nothing, when you come to a stand still
When you stop at a junction, the revs drop dramatically, almost to nothing. It does occasionally stall. Generally the range rover will idle fine at a stand still, for around 4 seconds before the revs drop. The revs will normally pick straight back up to idle and it usually only happens once when you stop. If it did happen to stall then you can always start it up again.
It only happens when the range rover is stopped and not when it is moving. You cannot predict whether it will happen or not , although it does happen most times when you stop.
We have replaced the idle control valve, the coil pack, air flow meter, engine temperature sensor, oxygen sensors, gearbox ecu and we have also downloaded the latest engine management program via autologic testbook. We have also reset the adaptations.

We are now stuck for what to do next, and any ideas or advice would be very apreciated.
Cheers John

[Rovin4life]

have you hooked up a fuel pressure gauge to it. Its a pain but it is on the backside by the coil.

have you checked fuel quality at all.

[shiftech]

Check all the rubber pipes going to and the plenum for air leaks

[rangerover2001]

Originally Posted by beezel

have you hooked up a fuel pressure gauge to it. Its a pain but it is on the backside by the coil.

have you checked fuel quality at all.

Hi thanks for the reply.
No we havent checked the fuel pressure. What sort of pressure should i expect to get and where would i connect it.
thanks again for the suggestion, i will look into it.
cheers john.

[rangerover2001]

Originally Posted by shiftech

Check all the rubber pipes going to and the plenum for air leaks

Thanks for the sugestion, we suspected a leak in the rubber pipes and checked it out but all was ok.
thanks for the reply,
cheers john

[Rovin4life]

You should have forty, but if it stalls it should still hold pressure.

heres an idea hook up a vacuum pump to the fuel pressure regulator and see the idle changes.

oh what is the fuel quality like, they didnt add diesel did they

[Paulo_Miguel]

Hello,

I have a similar problem on my 4.6, and changed the TPC - Trottle Position Sensor, and it´s fine now.

The TPC, mesure outside with a multimeter it as OK, but when working sometimes the revs are unstable.

Best regards