egine has no revs on drive when stooping at a junction

new to range rovers, bought 1998 DSE with 150k on clock very pleased with it except for one thing.
Occasionally when stopped at a road junction or just stopped when you press the accelerator engine stays at idling speed putting into neutral engine revs up normally.

If left for 5 10 minutes everything seems normal again has anyone had similar problems

thanks in anticipation

protium

t

Diagnostics required.

change your fuel filter