HELP when starting the car need to keep reves up or it cuts out

[NIBSWORLD 0]

Hi Guys

Need some help when i start the car first time of the day and this could be anytime of the day it cuts out if i keep the reves up to about 2000 for 30 secounds then slowly ease off it ticks over at about 600 if i go out in the car and say into a supermarket for an hour then come out and start the car its fine runs no problem its just that first start that it wont tick over on what could it be

N reg vr6 ob2 engine

any adivice would be great

thanks Nibsworld