crash_mat

Hi there I am new to this site. I have been reading posts where people have had problems starting their car when hot, but I have the opposite problem, it starts up but dies after a few seconds when cold, unless I keep it at 2500-3000rpm. I have checked the cold start valve and even tried with it unplugged but still no good. I have recently serviced it but the problem is still the same so just wondered if anyone can help. Thanks, Matt.